Fortress of Suomenlinna

Fortress of Suomenlinna

Built in the second half of the 18th century by Sweden on a group of islands located at the entrance of Helsinki's harbour, this fortress is an especially interesting example of European military architecture of the time.

Forteresse de Suomenlinna

Construite dans la seconde moitié du XVIIIe siècle par les Suédois sur un groupe d'îles situées à l'entrée de la rade d'Helsinki, la forteresse constitue un exemple particulièrement intéressant de l'architecture militaire européenne de l'époque.

قلعة سوامنلينا

تشكّل القلعة التي شيّدها السويديون في النصف الثاني من القرن الثامن عشر على مجموعة جُزر تقع على مشارف مرسى هلسنكي نُموذجاً مثيراً للأهمية للهندسة المعمارية العسكرية الأوروبية التي تجسد تلك الحقبة.

source: UNESCO/ERI



source: UNESCO/ERI

Крепость Суоменлинна (Хельсинки)

Построенная Швецией во второй половине XVIII в. на островах, расположенных у входа в гавань Хельсинки, эта крепость является особенно интересным примером европейской военной архитектуры того времени.

source: UNESCO/ERI

Fortaleza de Suomenlinna

Construida por los suecos en la segunda mitad del siglo XVIII, esta fortaleza ocupa un grupo de islas situadas a la entrada de la rada de Helsinki. Es un ejemplo particularmente interesante de la arquitectura militar europea de la época.

source: UNESCO/ERI


source: NFUAJ

Fort Suomenlinna

Het fort van Finland (Suomenlinna) is een interessant voorbeeld van de toenmalige Europese militaire architectuur. In 1747, toen Finland deel uitmaakte van het Zweedse rijk, besloot men om een fort te bouwen als belangrijkste basis voor de strijdkrachten in Finland . Een groep eilanden in de buurt van Helsinki werd uitgekozen voor deze burcht, die Sveaborg (‘Fort van Zweden’) werd genoemd. De bouw begon in 1748 met als doel de eilanden te verbinden en versterken zodat de toegang tot de haven gecontroleerd kon worden. Sveaborg was het grootste bouwproject in Zweden in de 18e eeuw; de bouwploeg bestond uit meer dan 6.500 Finse en Zweedse soldaten.


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© Suomen Ilmankuva Oy
Outstanding Universal Value

Brief synthesis 

Suomenlinna (Sveaborg) is a sea fortress, which was built gradually from 1748 onwards on a group of islands belonging to the district of Helsinki. The work was supervised by the Swedish Admiral Augustin Eherensvärd (1710-1772), who adapted Vauban’s theories to the very special geographical features of the region. The landscape and the architecture of the fortress have been shaped by several historic events. It has served to defend three different sovereign states over the years: the Kingdom of Sweden, the Russian Empire and most recently the Republic of Finland.

Covering an area of 210 ha and consisting of 200 buildings and 6 km of defensive walls, the fortress stretches over six separate islands. The original fortress was built using local rock and fortified with a system of bastions over varied terrain. The purpose of the fortress was originally to defend the Kingdom of Sweden against the Russian Empire and to serve as a fortified army base, complete with a dry dock. Sandbanks, barracks and various other buildings were added during the 19th-century Russian period. The defensive system was adapted to match the requirements of a modern fortress and developed in the 19th century using contemporary fortification equipment.

After Finland gained independence in 1917, the fortress was renamed Suomenlinna (or Fortress of Finland) and served as a garrison and a harbour. The military role of the fortress declined after World War II, and in 1973 the area was converted for civilian purposes. Since then, buildings have been renovated to serve as apartments as well as workspaces, to house private and public services, and for cultural purposes.

Today, Suomenlinna is one of the most popular tourist attractions in Finland and constitutes a district of Helsinki with 850 inhabitants. 

Criterion (iv): In the history of military architecture, the Fortress of Suomenlinna is an outstanding example of general fortification principles of the 17th and 18th centuries, notably the bastion system, and also showcases individual characteristics. 


Suomenlinna consists of several defensive and utilitarian buildings that blend the architecture and functionality of the fortress within the surrounding landscape. The property includes the islands upon which the fortress was built. This forms a consistent ensemble extensive enough to preserve and present the values of the property. Most of the fortifications and utilitarian buildings dating from the Swedish and Russian periods are well preserved. The fortress has only a few buildings dating from the Finnish era, but they retain their own distinctive identity. A sharp rise in sea level or increased rainfall could threaten the property. 


The fortifications and the various buildings, all dating from different eras, as well as the surrounding environment, help preserve Suomenlinna’s characteristics, particularly with regard to building materials, methods and architecture. Since Suomenlinna became a residential area, traditional construction methods have been favoured to ensure the preservation of the property, and are implemented in a manner that respects its cultural and historical values. 

Protection and management requirements

Suomenlinna is legally protected under national legislation. The fortification works are protected by the Ancient Act of 1963 and the church is protected by the Church Act of 1994. The Governing Body of Suomenlinna, a government agency under the Ministry of Education and Culture, owns most of the historical buildings in Suomenlinna. The Governing Body is responsible for the restoration and maintenance of the fortress. The activities are guided by the 1974 Management Plan, which has since been revised. The costs of the Governing Body, which employs around 90 people, are met using funding from the central government budget and from rental income. The Governing Body of Suomenlinna works closely with the National Board of Antiquities, Suomenlinna Prison and the City of Helsinki. Representatives of the local people have a seat in the Governing Body of Suomenlinna.

Suomenlinna is surrounded by open waters and nature reserves. The islands in its vicinity are used by the Finnish Defence Forces, or are subject to restrictive development plans. No changes to the surrounding area that could threaten the values of the property are planned for the near future. The buffer zone of Suomenlinna ends at downtown Helsinki to the north and the military district to the east and south. The island-based fortress is not threatened by city planning or traffic.

The possibility of a sharp rise in sea levels owing to climate change constitutes a potential threat to the property, as it would accelerate the erosion of coastal structures. Similarly, increased rainfall causes damage to wooden and stone structures. The increase in visitors has also caused sandbanks to become eroded during the summer. The erosion is managed by restricting visitors’ access to vulnerable areas during the summer months and regular reports are produced. The threats are recognized in the Suomenlinna Visitor Management Strategy from 2007 and the revised Management Plan from 2013.

Long Description

In the history of military architecture, the Fortress of Finland (Suomenlinna) is an outstanding example representative both of the general fortification principles of the period and of its specific characteristics.

In 1747, when Finland was part of the Swedish realm, the Diet in Stockholm decided to build a fortress to serve as the main base for the armed forces stationed in Finland. A group of islands close to Helsinki were chosen to be the site of the fortress, which was to be called Sveaborg, the 'Fortress of Sweden', and construction began in 1748. The purpose was to link and fortify several islands so that entry into the city's harbour could be controlled.

The work began in 1748 under the supervision of the Swedish Admiral Augustin Ehrensvärd (1710-72), an artillery officer of aristocratic background in his mid-thirties. He adapted Vauban's theories to the very special geographical features of Helsinki. Ehrensvärd's original plan was to build a chain of linked fortifications across a group of islands close to Helsinki and to fortify certain strategic points on land around the town itself. The second part of the plan was never carried out, but by the time of his death in 1772 Ehrensvärd had produced the chain of forts, collectively called Sveaborg (Swedish Fortress), that were to protect the approaches to Helsinki. By the end of the century the construction work was virtually complete.

One of the main reasons for building Sveaborg was to help Sweden counter the ambitions of Russia, whose principal military base in the Gulf of Finland was Kronstadt, commissioned by Peter the Great to protect the city of St Petersburg and as the home port of a new Russian Navy to challenge Swedish maritime power in the eastern reaches of the Baltic Sea.

Although Sveaborg was operational at Ehrensvärd's death, fortification continued. King Gustav III (1771-92) seems to have taken a close interest in the work. The fortress was occupied by the Russians after the war of 1808-9 (despite its reputation as being invulnerable); it was again strengthened and its name was changed to Viapori. Swedish power in the region gradually declined and in 1808 Sveaborg was surrendered to Russian forces. In 1855, during the Crimean War, Franco-British soldiers bombarded the fortress to no avail. However, reconstruction work and new construction were undertaken. Following Finland's independence (1918), the name was changed a final time to Suomenlinna (Fortress of Finland). 6 km of walls and 190 buildings have been preserved.

Located on islands off Helsinki, Suomenlinna is a unique historical monument and one of the largest maritime fortresses in the world. Its history is closely entwined with that of Finland and the Baltic region. Helsinki can also thank Suomenlinna for its early growth and prosperity.

Historical Description

In 1747 the Swedish Diet made a decision to fortify the eastern border and to establish a place d'armes on islands outside Helsinki. France, with which Sweden had a military alliance, financed a great part of the construction during the first decades.

Sveaborg was the largest construction project in Sweden in the 18th century. It was constructed under the supervision and direction of Lieutenant-Colonel Augustin Ehrensvard, assisted by the best Swedish engineering and mechanics experts. The fortress was constructed by soldiers in the regular army from all over Sweden and Finland. At its height, the construction crew totalled more than 6500. When Ehrensvard died in 1772, the fortress was virtually ready for use. The overall plan was revisecf in 1774.

European power politics also determined Sveaborg's fate. In the war of 1808-1809, which was a direct consequence of the treaties between Napoleon and Alexander I, Russia occupied Finland. Sveaborg surrendered and became a Russian garrison for the following 110 years. At the turn of the century there were about 4000 Russian soldiers in Sveaborg. The fortress remained in the state it had been under Swedish rule until the bombings during the Crimean War in 1855, when the British and French Navies ·fired on the fort. In the repairs and modernisation , undertaken after .that, some of the damaged buildings were torn down or made lower and a new coastal defence line of earth banks was constructed.

Before the First World War, Sveaborg, mainly serving as a depot area, formed part of the defence scheme, "Peter the Great's Sea Fortress". The intention was that Sveaborg, together with Tallinn, would block off the entire Gulf of Finland and guarantee the security of St Petersburg, the Capital of Russia. After Finland became independent in 1917, Sveaborg became a Finnish garrison and was renamed in Finnish as Suomenlinna. It served as a prison camp after the Civil War in 1918-1919. Suomenlinna was in military use for the last time during the Second World War when it served as one of Helsinki's air surveillance centres. It served as a garrison until 1972. Its use for tourism and recreation began on a larger scale after 1963 .

Source: Advisory Body Evaluation