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Bulwarked Fortifications of the "Raia" (Border)

Date of Submission: 31/01/2017
Criteria: (iv)(vi)
Category: Cultural
Submitted by:
Permanent Delegation of Portugal to UNESCO
State, Province or Region:
District of Guarda, Council of Almeida; Portalegre, Councils of Elvas, Marvão and Viana do Castelo, Council of Valença
Ref.: 6218

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The sole responsibility for the content of each Tentative List lies with the State Party concerned. The publication of the Tentative Lists does not imply the expression of any opinion whatsoever of the World Heritage Committee or of the World Heritage Centre or of the Secretariat of UNESCO concerning the legal status of any country, territory, city or area or of its boundaries.

Property names are listed in the language in which they have been submitted by the State Party


Name of element

Central Point




No. in the Military Map of Portugal

Border Garrison Town of Elvas
and its fortifications

Castle’s Keep

38º 52’ 50.413’’N

-7º 09’ 51.822’’W



Stronghold of Almeida

Liberty Square

40º 43’ 29’’ N

-6º 54’ 23’’ W



Fortress of Marvão

Pelourinho Square

39º 23’ 37.58’’N

-7º 23’ 34.81’’W


336; 348

Fortress of Valença

Republic Square

42º 10’40.93’’N

-8º 38’40.96’’W



Extending from the mouth of river Minho in the North, to the mouth of river Guadiana in the south, a part of the current Portuguese/Spanish border dates to the ancient County of Portugal. From the Treaty of Zamora (1143), which marks the birth of Portugal, to the episode of the “Reconquista” that culminated in the Treaty of Badajoz (1267), which attributed the Algarve to Portugal, and the Treaty of Alcanizes (1297), a separation line was established that was rarely reviewed throughout more than 700 years.

However, due to geomorphological, strategic or even economic motivations, a contact strip has always existed between both sides, a more or less ample territory, a “no-man’s land” that, despite being continuously disputed economically by both parts and often the trigger for small conflicts, frequently acted as a “buffer zone”, mitigating any greater tensions since it has always been an area of exchange and interaction between people.

This is the area of “A RAIA”, in Portuguese, or “LA RAYA”, in Spanish, materialised by one of the most ancient territorial separation lines in Europe, which was structured throughout the centuries by an urbanisation process around fortified urban nuclei, forming opposite pairs that “watched” each other across the border.

The survey and cartographical representation of this Portuguese-Spanish raia [border] were for the first time drafted under the auspices of king D. Manuel II, result of the work carried out by Duarte D’Armas between 1509 and 1510, the famous Livro das Fortalezas [Book of the Fortresses], in which the plants and views of the Portuguese border fortification are drawn.

Also, and still during the reign of D. Manuel II, a separating line between Portugal and Spain was physically delimited by milestones.

It was, however, during the reign of D. João III that the first map of Portugal as a Continent was drawn, although the original copy mapped by Fernando Álvares Seco and printed in Italy in 1561-62, in Michele Tramezzino’s typography, is still unknown.

If the military and diplomatic concerns could already be felt in greater detail and rigour dedicated to the frontier representation of the 16th century cartography, it is in the context of the Portuguese Restoration War that cartography specially served military purposes; on this matter, the map of Portugal by Pedro Teixeira Albernaz, dated from 1662, stands out, in which the border limits are represented, in the dry border, by a double dashed line, including also at that section and in great detail, the main fortification works on both sides of the border, highlighting those featuring a “modern” walled enclosure.

Of these fortified structure, a few stand out that, due to their strategic location in the most important natural passageways crossing the more than 1300 km of the raia, limited by territorial milestones or water lines, had their ancient walls replaced by new or significantly reinforced ones, adapted to the “new art of war”.

Designed as integral portions of the defensive systems of the territories of Portugal and Spain, consolidating the oldest European border, the bulwarked fortifications of the raia created opposing pairs, as it is illustrated by the pairs of Ínsua and Caminha/A Guarda, Valença/Tui, Chaves/Verín, Almeida/Ciudad Rodrigo, Marvão/Valencia de Alcántara, Elvas/Badajoz, Olivença/Alconchel and Alcoutim/Sanlúcar de Guadiana. The uniqueness of some of them, like the Stronghold of Almeida, the Garrison Border Town of Elvas and its fortifications, the Fortress of Marvão and the Fortress of Valença, due to their monumentality, preservation status, greatness or historical importance, transforms them into heritage testimonials of Outstanding Universal Value, worthy of special protection that can only be achieved by their successive nomination as World Heritage.

Stronghold of Almeida: It is a fortress-town with an almost perfect star shape, according to the constructive principles of the bulwarked system, of which it is an outstanding example. It is one of the most complete and well preserved Portuguese fortresses.

The fortification is composed by 6 bullwarks and 6 ravelins, surrounded by a striking enclosure of covered walkway ditches. It communicated with the outside via two double gate systems (São Francisco and Santo António). The walls are made of stonemasonry of large regular granite blocks.

The bullwarks feature more than 100 cannons on their parapets, also including mortar platforms and underground magazines with two vaulted compartments. The Bullwark of Arsenal was adapted (1766/68) to a military Bread Factory. At the Bullwark of São João de Deus, one finds the Casemates (a notable set of 20 compartments and access gallery with barrel vaults, protected with special “bombproof” roof and communicating with a central rectangular square).

The Double Ravelin is the most elaborated Vauban-like advanced work (with a ravelin and demilune and intermediary ditches interconnected via a drawbridge, still featuring the vaulted postern with a curve plant). The Ravelin of the Paiol has two buildings (magazine and chapel), with access ramp from the ditch. At the Ravelin of Santo António, as at the ravelin of São Francisco (mid-curtain between the bullwarks of São Francisco and São Pedro), one finds the Double External Gate of São Francisco or Cruz.

There are also three important vaulted posterns (São Pedro, São João de Deus and Horta do Governador), connecting the inside of the stronghold to the ditches.

The scale of the fortification may be confirmed with the following data on its construction:

  •  Perimeter of the fortification (as measured at the covered walkway) – 3180 m / Magisterial line of the six bullwarks – 2442 m/ Length of magisterial line and edges of the ravelins – 4545 m / Urban area (as measured by the escarpments of the curtains and necks) – 11.83 ha (perimeter of 1292 m) / Global surface of regular granite masonry walls – 19.94 ha / Area of the six ravelins – 3.90 ha / Sum of walled areas – 23.84 ha / General surface of the ditches – 9.70 ha / Area of the polygon of the fortifications (as measured by the implementation of the counter-escarpment) – 33.45 ha / Area of the general polygon of the fortifications (as measurement by the implementation of the Covered Walkway) – 37.52 ha / Global area, with glacis (as measured by the perimeter of the current peripheral way - 3272 m) – 63.92 ha.

Inside the fortification lines, one finds the archaeological site with the ruins of the late 13th century Medieval Castle, which bears an extraordinary interest for the evaluation of the Portuguese military architecture, including Manueline Transitional Architecture, along with the symbolism of the identity idea of the border expressed in the Treaty of Alcanizes, in 1297, which established an alliance of friendship and mutual defence between Portugal and Castile, leading to the peace between the two nations.

The two double Gates of the stronghold are, for their type, one of the best examples in Portugal. Some remarkable buildings still operate today, including the enormous 18th century Quartel [Barracks] das Esquadras and Corpo da Guarda Principal [Main Guard’s Corps] (currently serving as the Town Hall) and the Church of the Misericórdia (17th century). 

Garrison Border Town of Elvas and its Fortifications: Shielding the frontier between Lisbon, the capital of Portugal, and the capital of Spain, Madrid, among an undulating riverside landscape, the garrison border town of Elvas was comprehensively fortified between the 17th and 19th centuries, becoming the largest bullwark dry ditch system in the world, with peripheral fortresses built on the surrounding hills to better accommodate the needs of adaptation of the defensive war.

The city was supplied with water by the 7-km long Aqueduct of Amoreira built between the late 15th century and early 17th century, a key element for the town to withstand a long siege. Within its walls, the town contains large barracks and other military buildings, as well as churches and monasteries, some of which were adapted to military functions. This World Heritage Site includes seven components: The Historic Centre, the Aqueduct of Amoreira, the Fort of Santa Luzia and the covered walkway connecting it to the Historical Centre, the Fort of Graça, the fortlets of São Mamede, São Pedro and São Domingos.

The historical centre with its castle, remnant walls and civil and religious buildings demonstrate the development of Elvas as three successive walled towns from the 10th to the 14th century and its subsequent integration into the major fortification works of the Portuguese War of the Restoration period (1641-68), when a wide range of military buildings were built due to its role as a garrison town.

The bulwark fortifications of the town and the peripheral Fort of Santa Luzia and Graça and fortlets of São Mamede, São Pedro and São Domingos reflect the evolution of the Dutch system of fortification into an outstanding dry-ditch defence system.

The construction of these fortifications began in 1643 and comprises twelve forts inserted in an irregular polygon, roughly centred on the castle and making use of its landscape of hills. The bulwarks are battered, surrounded by a dry ditch and counterscarp and fortified by several ravelins. The fortifications were designed by the Dutch Jesuit Cosmander, based on the treaties of fortification engineer Samuel Marolois, whose work, along with the one of Simon Stevin and Adam Fritach launched the Dutch school of fortification worldwide. Cosmander applied the geometric theory of Marolois to the irregular topography of Elvas to produce a defensive system considered a masterpiece of its time.

In the 18th century the Fort of Graça was constructed in response to the development of longer-ranged artillery, as well as four fortlets to the west.

Fortress of Marvão: The medieval fortification system of Marvão, with its castle and urban wall, was, broadly speaking, maintained until the 17th century, when Marvão saw its importance emphasized within the context of the Portuguese War of the Restoration. Under the energy of abbot D. João Dama, it was partially remodeled with star-shaped bulwarks protecting the main gates and the outermost limits of the fortress.

Built on a high and almost inaccessible boulder, the Castle of Marvão was a strategic detention fortification, oriented towards the border, which is only 13 km away. It was also an efficient refuge and an extraordinary location for observation and surveillance, since it clearly dominates the second most important penetration route of the armies of the neighboring country, coming from Valencia de Alcántara.

The Castle, whose first documented references dates to the 9th century, occupies the highest area and has two interconnected enclosures, following a Moorish model, the albacar and the alcázar.

The albacar, much higher than the alcázar, has a salient angle and a postern to the west. In the opposite section, another postern with an anthropomorphic arch, opening towards a barbican. The entire wall has a chemin-de-ronde and inclined parapet. At the southeast portion, a square tower overlooks the entrance, defended by four round towers, and two fortified enclosures, with cannons to the southwest. Inside the albacar, southeast portion, the Forno do Assento and, opposite, the Guard’s Corps. At the entrance area, one finds the Great Cistern (15th/16th centuries), with a rectangular plant and a cannon vault, supported by stonework ribs with a round arch.

The alcázar can be found at the northwest top and the entrance is made via a barbican, with a pointed arch, which, in its west side, incorporated a fortification with cannons facing the albacar. The courtyard contains a small cistern, two towers and a round tower. The Keep, in the south angle and with a square plant, has primitive features, with slits, a round arch door with a smooth tympanum resting over concave imposts, forming an anthropomorphic arch. The single compartment on the Tower provides access to the chemin-de-ronde. On the courtyard, there are three buildings, remains of the old magazines and Modern Age armouries. To the northeast, the postern that gives access to the barbican and, from there, to the outside, via a manhole tunnel and round arch door. Fortifying this area, one finds a bulwark, to the west, interconnected through the old barbican with another bulwark, to the north.

The urban wall (14th-16th centuries) outlines a roughly trapezoidal design, disrupted, in the neuralgic sections, by rectangular turrets, round towers and bulwarked fortifications protecting two gates and a wicket.

Similarly to all other fortifications composing the first line of defence, the Fortress of Marvão suffered a metamorphosis throughout time, in an attempt to answer to the new war technologies. During in the 17th century and first half of the 18th century, following the War of Restoration and the Succession War, the bulwarked fortification reinforced the entrances in the urban enclosure, while reinforcing the castle’s defence at its most vulnerable area, the continuation of the crest towards the northwest. Given the orography of the location, the defence of the fortification only needed to be reinforced on a small number of location to continue being inexpungable until the Fortress was dismantled in the 19th century.

Fortress of Valença: It is here that older material remains of a permanent and structured occupation of the place or site that corresponds to the current fortress can be found. It dates back to 1st century AD and was probably a settlement surrounded by a wall – a traditional “hillfort”.

There and within the context of the materialisation of the defence of the border line of river Minho, King Sancho I, in the beginning of the 13th century, it is located the fortified medieval village of Valença, called Contrasta at the time. In 1297, it received a charter letter from D. Afonso II, which was confirmed by King Afonso II in 1262, changing its name to Valença (its current denomination).

Throughout the centuries, the defence of the urban cluster and the border line called for a constant renovation of the defensive system, to keep up with the technological advances in warfare, culminating, in the 17th century, in a double enclosure bulwarked fortification, part of which adapted the pre-existing medieval fence.

In fact, between the final decades of the 17th century and the first quarter of the 18th century, the village of Valença became the object of a new and ambitious bulwarked fortification project, designed by

Michel de Lescolles and his disciple Manuel Pinto de Vilalobos, constructing one of the most striking Portuguese fortified compounds of modern times, stretching over an area of approximately 50 Ha.

Constituted by two main interconnected enclosures, the Coroada and the Magistral (or Vila Velha), the modern fortress of Valença, whose original project was never completely executed, has 10 bulwarks and 2 demi-bullwarks, 5 ravelins, 5 ramparts, 6 redans, 2 counterguards, 2 couvrefaces, 1 tenaille, 6 gates, 3 posterns and 33 sentry boxes, forming a set whose dimension and architectural characteristics are, indeed, expression of the importance of the fortress, powered by 214 cannons, which dominated over the most important road between the North of Portugal and Galicia.

Its implementation on a hill overlooking the river Minho grants it a unique and peculiar shape, characterised by the double pentagonal plant and profile divided into different defensive levels, from the great exterior esplanade to the parapets, higher than the bulwarks, encompassing a total area of 47.6 Ha.

The first level is defined by the covered walkway surrounding the ditch, in the interior limit of the esplanade, encompassing an area of 21.894 Ha; a second level corresponds to the limit of the defensive structure that includes the faussebrayes, with an area of 12.198 Ha and the ravelins with an area of 8,429 m2; the third level, defined by the highest platform of the bulwarks, totals an area of 10.278 Ha.

The urban nucleus comprises an area of 212,233 m2, made up of 224 buildings forming 32 blocks, which are distributed along both enclosures (Magistral and Coroada). Inside the walls, one should emphasise the military buildings, especially Marte’s Magazine (1715), Açougue’s Magazine (1713), Palace of the Military Government (1783), Military Chapel of Bom Jesus (1700), as well as 10 casemates, distributed across the Fortress. We can also highlight some religious buildings, such as the Church of Colegiada/St. Stephens (1283), the Mother Church/Saint Mary of the Angels (1217) and some buildings with great architectural and historical value, such as Casa do Eirdado (1448), the old Aljube (1728) and the current building of the Town Hall.

In the 20th century, even though its military function was abandoned, the fortress remained a lively, singular and unique space, open to the world, with a historic, cultural and economic expression in the Iberian dimension.

Justification of Outstanding Universal Value

The modern fortresses of the Portuguese-Spanish raia are the example of the complete mastery of the art of bulwarked fortification, which, already since the 16th century, the Portuguese architects and military engineers applied in Africa, Brazil and Asia, as well as Castilians in the so-called New World.

The architects and military engineers that projected the bulwarked fortification of the Portuguese- Spanish border did not simply repeated standardised models; rather, they dared to innovate them building unique solutions, determined both by the clever adaptation to each location’s geographic specificities – be it plains, mountains or the banks of great rivers – and by diversified plastic enhancement of each construction, with a superb architectural quality.

Within the context of the history of world fortification, the bulwarked fortification of Almeida, Elvas, Marvão and Valença bear, in fact, proof of the equilibrium achieved in the art of attacking and defending, supported by the technical competence that originated in knowledge and experience centres of different origins, fostered by the active policy of the Portuguese crown.

They are also a remarkable testimonial of a military landscape of the border, showcasing the Portuguese desire of preserving its territory and sovereignty, preserving the aspiration for autonomy that most European Nation States achieved during the 16th-17th centuries.

Criterion (iv): The Garrison Border Town of Elvas and its Fortifications, the Stronghold of Almeida, the Fortress of Marvão and the Fortress of Valença are exceptional examples of the type of 17th and 18th century bulwarked construction that was developed as consequence of the power plays that reconfigured Europe from the 17th century onwards.

The extraordinary complete materialisation of the modern fortified border of the Portuguese raia implied, over an extremely short period, a concentration of quite ample scientific and technical effort and with a reach never achieved in any other location.

They represent at the same time, the technical and practical developments of the 17th and 18th century European military architectures and technologies, bearing witness to the propagation of the bulwarked military engineering models experimented throughout Europe by Italian, Dutch, French, Swedish and Knights Hospitaller engineers, which the Portuguese school of military engineering assimilated, developed and expanded for the “new world”:

Almeida is a great structure and was certainly one of the first great materialisations of the design of bulwarked fortifications, being one of the most avant-garde and well preserved examples of the 17th century, representing a singular chapter of the Portuguese modern border, expressed in its iconic star shape (anticipating aspects of Vauban’s designs, towards the end of his activity, specifically the strongholds of Longwy and Neuf-Brisach).

The Garrison Border Town of Elvas and its Fortifications are an excellent example of a garrison town and of a walled defensive system with the largest dry-ditch in the world.

Marvão, due to the wise integration of bulwarked structures, which expand the perched medieval fortress at the top of a quartz escarp, is an impressive testimonial of the human creative genius, which, in here, due to the symbiosis achieved between Culture and Nature, creates a bedazzling landscape, right at the heart of the Natural Park of Serra de S. Mamede. The Fortress of Valença, due to its riverside location, dimension and form, with two interconnected polygonal enclosures (Coroada and Magistral), is an exceptional example of a bulwarked fortification adapted to the terrain’s topography and of the integration of the pre-existing urban mesh.

Criterion (vi): The Portuguese bulwarked fortification followed a whole European political-military process that marked the independence of the country within Iberia.

The Garrison Border Town of Elvas and its Fortifications, the Stronghold of Almeida, the Fortress of Marvão and the Fortress of Valença are not only directly connected to the history of Portugal and Spain, but also to the history of Europe and other continents. A history of wars, of trade relations and cultural landmarks, of exchange of knowledge, uses, traditions and ideas, throughout many centuries. A history that transcended the border and time of both States, influencing and being influenced by Europe and the world beyond the Mediterranean and the Atlantic.

These war structures, part of a sophisticated defence system created in the 17th and 18th centuries, with architectural attributions that also meant to cause an impact, communicating invincibility, maintain the symbolic and unique attributes of beauty, of monumentality and greatness that now attract visits, transforming the sites in locations of human life and socialisation, servings the peace and the relationship amongst people.

This multidimensional historic tradition has a clear outstanding universal meaning, which is also strongly stated in the binomials Almeida-Ciudad Rodrigo, Elvas-Badajoz, Marvão-Valencia de Alcántara, Valença-Tui.

Facing Ciudad Rodrigo, Almeida is, from its beginning, the most important anchor for the definition of the limits of the Portuguese State, originating the border with the oldest limits and peace treaty, still in force – the Treaty of Alcanizes, 1297, thus becoming directly associated to the idea of the National Identity of Portugal.

In Elvas, the Portuguese border has the pinnacle of its fortifications, exemplary demonstrating how Portugal maintained its border against the powerful 17th century Spain. Opposite to the robust stronghold of Badajoz, Elvas is an exceptional example of the combination of military and civilian components, which influenced its urbanism and its residents’ daily lives until today.

For its residents, Marvão was a land often defined as a town, other times as a stronghold and sometimes as a border and “dry harbour”, exercising its role as a customs location. This was and is a space of experience and tradition of good neighbours, illustrated by the oldest neighbouring agreements with Castelo de Vide, Portalegre and Valencia de Alcántara, regarding hills, pastures, water use and cattle circulation.

Valença, located on the border, facing the Spanish town of Tui, on the strategic crossing of the land and river roads connecting the north of Portugal to Galicia, was always a place of cross border relations, perfectly highlighted by the circumstance that, although belonging to the Portuguese crown, it was under Tui’s ecclesiastic administration until the 16th century.

More than for its monumentality, Valença is part of Portugal’s identity imagery, even of the Iberian Peninsula, mostly due to the immaterial dimension of the site on both historical, cultural and economic levels, as may be attested by the thousands of pilgrims to Santiago de Compostela that cross it every year.

Statements of authenticity and/or integrity

The analysis and comparison of original plans and drawings with the current surveys, the military reports, the photographs and the descriptions attest the unquestionable authenticity of the properties. Also, the form and materials of the fortifications are still in virtually the same state as when they were rendered obsolete in the 19th-20th century. The military and religious buildings have largely retained their function or another appropriate use until today. Its border military identity remains unchanged and has been preserved and enhanced through monographic museums.

In the case of the Garrison Border Town of Elvas and its Fortifications, the large collection of original plans and drawings, military reports, photographs and descriptions testify its authenticity, as recognised by the World Heritage Committee in 2012.

The conservation and maintenance process of the Stronghold of Almeida kindles the principles of the Nara Document, as supported by the guidelines expressed in the Venice Charter. Even the ruins of medieval times and of transition to Modern times integrate an important archaeological site. The main reason for the conservation of the heritage carried out throughout time has been justified by the iconic strength of the grand geometry of the fortification’s outline, with the purity of the drawing of the walls and their defensive systems. On that matter, the conservation of the glacis is an aspect that underlines the recognised importance of the fortress star-shaped design and its entire understanding as a technological and architectural compound invented in the 17th century.

The different plant of the Fortress of Marvão – the plant by Nicolau de Langres, probably executed in 1644, the plant by Miguel Luiz Jacob, 1755, and the plants of 1812 and 1814 - document the architectural evolution of the property and the comparison of the most recent one with the current fortification attests its integrity and authenticity. The fortification, impeccably preserved, has been continuously rehabilitated, starting from the beginning of nationality until the 20th century. For the integrity and authenticity of the property, the fact that its urban mesh is confined to the enclosure of the walls is also important, only escaping them for the building of the Franciscan convent of Our Lady of the Star, and the maintenance of military functions which originally justified its construction until the second half of the 19th century.

The Fortress of Valença is preserved virtually intact in its shape, as may be attested in the original drawing and plants, from the 17th and 18th century, with a bulwarked system adapted to the power of the artillery.

Without hindering its historic and original authenticity, both in the walls and in the buildings within the two-walled enclosure, the property suffered the natural adaptation to new contemporary uses, trade and culture centres and public buildings.

According to the previous perspective, the last requalification interventions of the historic centre of Valença intended to improve the living conditions of both population and visitors, without having to forget the Property’s authenticity and integrity or its unique identity, thus becoming a place of singular cultural richness for humanity.

All elements necessary to express the Outstanding Universal Value of the property are included within the areas proposed for each property.

The respect for the proper use of materials and the maintenance according the military compounds throughout the centuries (up to the first quarter of the 20th century) were vital contributions for ensuring the integrity of the built heritage.

The unavoidable rehabilitations carried out throughout time were conducted in their own time, with its own architecture, based on its context and never anachronistically, thus adding a unique dimension of actualisation in continuity.

Furthermore, the conservation and maintenance process implemented by different responsible entities, following their listing as National Monuments, were according the international principles and guidelines on heritage interventions.

The possible vulnerability of the properties against urban expansion, potentiated by the near crossing of great communication routes, is secured by the proposed large buffer zones, which also ensure the maintenance of their visual integrity.

The responsible entities have been promoting, during the last years, the conservation and rehabilitation of significant portions of the Properties and are aware of the isolated existence of vacant buildings, implementing, within their legal reach, protecting actions that prevent vandalism and their deterioration.

Comparison with other similar properties

The Portuguese bulwarked fortifications are inscribed in the history of the European civilization as one of the most significant cultural facts, for its antiquity and maintenance of the border defined in the Middle Age, translated in the diplomatic document related to the establishment of sovereign limits, the oldest of its kind still in force – Treaty of Alcanizes (1297). This delimitation corresponds exactly to the construction of the set of modern fortifications, during the War of Restauration (1641-1668), making way to a military architectural heritage that must be understood, due to its conservation and authenticity, as an asset with a unique character in the world. Although this is living heritage, it is still possible to compare the “Raia” of Portugal with the value of the historic-archaeological properties listed by UNESCO of the “Limes Romano” and the Great Wall of China (both inscribed in 1987).

This frontier was successfully executed by Portugal, within an avant-garde conception of fortification, revealing its character as a system and complement of the construction over at the Spanish space, throughout the 1300 km of the raia, where we can still find sociological and cultural traits unique to the communities living at the border and where one can always witness bonds and conviviality, which oppose the traits of a cultural peace with a country’s identity affirmation needs.

Bearing witness to the propagation of the bulwarked military engineering models experimented throughout Europe (with a remarkable mastery by the Italian, Dutch, French, Swedish and Knights Hospitaller engineers) and its acceptance and later diffusion in the “new world”, the bulwarked fortification of the Portuguese-Spanish raia was not projected independently, but rather as parts of a complex and integrated defensive system of the territory, structured to the North by the subsystems of Valença and Chaves, to the Centre by the subsystem of Almeida and to the south by the subsystem of Elvas.

The fortresses of Almeida, Elvas, Marvão and Valença are knitted into the fabric of long time, becoming built expressions of the History of Portugal, of Europe and of the World. In the originality of the construction of the modern frontier, during the War of Restoration, defensive methods and strategic visions were tested that anticipated immediately consecrated solutions, particularly the works of Vauban, as it is the case of the “pré-carré” implemented in the front border of the Alentejo/Extremadura.

Within the context of the bulwarked fortification already listed, both individually and serially, as World Heritage, representing the multiple European schools of bulwarked military architecture, which were developed throughout Europe since the 16th century and later disseminated across the world, one should highlight the absence of a set linked to a historic border that has remained in force for more than seven centuries.

To compare Almeida, Elvas, Marvão and Valença with other properties of outstanding value, one should firstly mention, as chronological reference, the novelty that the case of the “Cité Portugaise” (El Jadida/Morocco) represented in 1540, the first European bulwarked town, with an entirely new conception.

We continue with cases that are already World Heritage sites: the great Portuguese Fortress of Qal’at al-Bahreïn, in Bahrein (c. 1560), built after the construction of the Fortress of Hormuz, carrying out a superb Avant-guard bulwarked fortification programme across the Persian Gulf, a clear exercise of the definition of the limits of the Sea Empire of Portugal against the Ottoman Empire.

For the expansion of such sovereignty of Portugal in the Indian Ocean, we find a remarkable predecessor (the first construction made by European in the eastern part of the world: the Kilwa Kisiwani, World Heritage of Tanzania, making also a reference to the Fortress of S. Sebastião in the Island of Mozambique/Republic of Mozambique, an important strategic port in the Indian commercial route, where the Portuguese built, in the 16th century, one of the most impressive bulwarked fortification in southern Africa.

Also, and still in UNESCO’s World Heritage List, one mentions, in Kenya, the Portuguese Fortress of Mombasa – the last great reinforcement of fortification, in the late 17th century, for the operation of the Eastern Sea Empire.

One may also draw a comparison to the universe of the Expansion of Spain in the Caribbean, starting by the great set built by the dynasty of the Antonelli engineers, of which the fortifications with the city of Old Habana (and also the Fortress of Tres Reys del Morro, 1589), the Fortress of San Pedro de la Roca del Morro (1638), in Santiago de Cuba, and the Fortress of San Felipe del Morro (1591), in San Juan de Puerto Rico, must be emphasized.

We must also emphasise the Fortress of San Juan de Ulúa, facing the city of Veracruz, in Mexico, and obviously, the Castle of San Felipe de Barajas (16th-17th centuries), considered the greatest Spanish military work in the New World, located in Cartagena de Indias, Colombia. In Europe, we find various examples, but, to be succinct and to highlight the great genius of bulwarked fortification, one mentions, in France, the 12 Vauban sites already inscribed on the World Heritage List, whose work became an example of the defensive system of a globally conceived border for Louis XIV’s France. The Portuguese bulwarked fortifications of Almeida, Elvas, Marvão and Valença may be compared with some of the extraordinary works of Sébastien le Prestre. In addition, when we make a reference to the modern production of military buildings, generally called “Vauban-like style“, it becomes evident that the raia of Portugal, within the European panorama and after the French case and Malta’s specific situation, considering the destruction and reconstructive adaptations that took place in most countries (as, for instance, Belgium, The Netherlands or Germany), is the system that presents, after observing its genius, the greatest highlight as a set, given the authenticity and value of the heritage under analysis.