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Chankillo Astronomical Complex

Date of Submission: 18/01/2013
Criteria: (i)(iii)(iv)
Category: Cultural
Submitted by:
Permanent Delegation of the Republic of Peru to UNESCO
State, Province or Region:
Casma province, Ancash region
Coordinates: N8942566 E803325
Ref.: 5792
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Chankillo is an archaeological complex with ritual, astronomical, administrative, and defensive functions.  Its astronomical function defines its universal value.  Through ample evidence, it has been shown that between 500-200 BC people at the site made direct observations of the movement of the Sun with the purpose of regulating seasonal events such as religious festival and the keeping of a seasonal calendar.

Unlike other so-called “observatory” sites around the world, which mark unequivocally only one or two dates, solar observations at Chankillo covered the span of its annual cycle.  Through sunrise and sunset observations of solar alignments over an artificial horizon, it was possible to identify with great precision the dates of solstices and equinoxes, as well as any other date throughout the seasonal cycle of the sun. In this sense, the Chankillo astronomical observatory is unique and exceptional, not only in Peru or in the Americas, but worldwide.

General Description: Chankillo is found in the Ancash region, Peru, 365 km north of Lima, and 15 km from the Pacific coast. Lying to the west of the Andes mountain range, this is one of the world’s driest deserts, a landscape of foothills, valleys, and plains that has geologically remained relatively unchanged since the Pleistocene.  In detail, Chankillo lies adjacent to the irrigated valley of the southern branch of the Casma/Sechin River basin, facing the rugged foothills of the western slopes of the Andes.  Like many of Peru’s coastal valleys, the Casma and Sechin valleys have long been an ‘oasis’ for settlement in an otherwise inhospitable desert.

Archaeological sites such as the Sechin Complex, Pampa de las Llamas-Moxeke, Las Haldas, El Purgatorio, and Manchan, demonstrate a long period of occupation (4500 years) from the late Preceramic Period to the Incas, suggesting that the Casma province has always been an important regional ceremonial center. Notwithstanding the recently revealed significance of Chankillo, sites in Casma relating to the Initial Period are unequalled nationally in terms of their size, quality, and ‘public architecture’. It is now only the ceremonial structures that survive, generally using spaces that would not compromise maximum use of the riverside land for agriculture. The less robust residential sites and cemeteries, perhaps more closely associated with the cultivation zone along the rivers, are no longer visible.

Dozens of 14C dates, ranging 2350-2150 CalBP place the construction, occupation, and abandonment of Chankillo within the late Early Horizon period (500–200 BC) of the central Peruvian chronology (Burger 1995).

The site is spread over 4 sq. km, which includes various occupations and several monumental stone and mortar constructions, originally plastered and painted with ochre, tan, yellow and white, sometimes bearing painting or textured with finger impressions.

The main constructions at the site define three sectors, which are described as follows.

Sector 1: The most outstanding feature of Sector 1 is an oval-shaped hilltop building known as the Fortified Temple.  A massive construction, located strategically 180 m above the valley floor, it is composed of three central structures surrounded by concentric defensive walls.  At its center, two identical buildings with circular ground plan and a rectangular building are surrounded by a large platform with parapets, which serves as the innermost defensive wall as well.  The twin buildings are composed of a pair of concentric circular walls with three restricted-access gates, and may have served as the final level of refuge for small groups.

The rectangular building is a temple, or palace, oriented to the December solstice sunrise.  Its front atrium is a U-shaped two-tiered platform with dual staircases on each level.  The rooms behind it, sometimes bearing mural decoration, were possibly used for ritual and elite habitation.  Excavations at this inner temple revealed the intentional destruction of its walls, pillars, and religious images, the possible looting of objects, and its entombment under a thick layer of rock and debris.  It was probably due to a violent conflict with an outside power, concluding with the defeat of Chankillo and the abrupt abandonment of the site (Ghezzi 2006).

The outer defensive walls surrounding the central platform are massive, in some places standing 8m.  These are complex walls, made up of parallel wall sections with in-between fill.  Wall tops were accessed through staircases spread around the perimeter at regular intervals.  There were nine baffled gateways, protected with parapets, top rooms hidden from outside view, false corridors, and other strategic measures.  Though their defensive function has been ably questioned (Topic and Topic 1997), available evidence indicates their main purpose was to provide a high level of protection, ultimately unsuccessful, to the inner temple of the fort.

Sector 2: East of the Fortified Temple is Sector 2, where we find a ceremonial area and its main feature, the Thirteen Towers.  These are a row of thirteen constructions placed along the ridge of a low hill at the center of the site.  They are elevated buildings with summit access by inset staircases on their north and south sides.  Their ground plan varies from rectangular to rhomboidal.  Their size (75–125 m2) and height (2–6 m) vary widely: the northernmost towers are taller than the rest, apparently to compensate for the drop in elevation of the natural hill on which they rest.  Nonetheless, they are regularly spaced: the gaps between the towers range only from 4.7 to 5.1 m.

The towers were flat-topped, originally forming a smooth, “false” horizon as viewed from the lower ground to the west or east.  No artifacts remain on the summits, yet the staircases strongly suggest that these surfaces were occupied at special times.  Ascension to the towers may have been important ritually, yet because their staircases are narrow (1.3–1.5 m wide), and their length (1.3–5.2 m) and height (2–6 m) vary in proportion to tower dimensions, several of them are too steep to climb.  The importance of the concept of duality has been amply discussed for the Central Andes, and its manifestation in the dual staircases at the towers, the layout of rooms within buildings, and the use of the double step-motif in sacred architectural elements and pottery vessels at Chankillo reflect the great symbolic importance of the Thirteen Towers.

The line of towers runs north-south, although towers 11–13 are twisted around towards the south-west.  In addition, Towers 11-12 cover the largest ground.  This may suggest that Tower 13 was intentionally “hidden” from some eastern viewing positions.  Yet the azimuths of the gaps between the towers, which vary progressively, north to south, from approximately 90°–270° to 120°–300°, suggest something else: that the purpose of the variations in the orientation of the tower axes was to orient the gaps between the towers towards a group of buildings within a walled enclosure to the west.

The best preserved of these buildings is 53.6 m long, 36.5 m wide, and  has an outer corridor running 40 m along the south side of the courtyard.  This corridor connected a restricted doorway on the north-west side with an opening on the southeast side that was unobstructed and directly faced the towers 235 m away.  However, the southeast doorway, unlike every other doorway at Chankillo, did not have the typical barholds, or niches where a pin was firmly tied into the stone masonry and presumably used to attach a wooden door.  In other words, it was a doorless opening.  This corridor, then, was a unique construction that ran alongside the courtyard building but never led into it.  Its purpose was, apparently, to channel movement from its restricted entryway to its doorless opening directly facing the Thirteen Towers.

From this western observing point, the spread of the towers along the horizon corresponds very closely to the range of movement of the rising and setting positions of the Sun over the year.  This in itself argues strongly that the towers were used for solar observation.  From this observing point, the southern slopes of Mucho Malo mountain, at a distance of 3 km, meet the nearer horizon (formed by the nearby hill on which the towers are constructed) just to the left of the northernmost tower (Tower 1), providing a 13th “gap” of similar width to those between each pair of adjacent towers down the line.  During the June solstice, the sun rises in this position; conversely, during the December solstice, it rises directly to the right of the southernmost tower (Tower 13).

Sector 3: This is a public area composed of a plaza surrounded by buildings, among them a complex of interconnected rooms, corridors, and patios, with associated facilities for the serving and storage of drinks directly southeast of the Thirteen Towers.  A small staircase on the eastern perimeter wall is apparently the single point of access to the building´s interior, and leads into a large patio surrounded by a U-shaped platform with inset staircases that distribute traffic towards the different rooms and courtyards.  The pattern of circulation suggests a complex spatial organization.  Towards the interior of the building, the rooms are reduced in size, but gain in elevation and wall height, and have a more restricted control of access.

Sector 3 was probably a setting for ceremonial feasts. In several spots within the plaza were found surface offerings of ceramic panpipes and thorny oyster (Spondylus) shells, and middens near it contain the remains of serving vessels, ceramic panpipes, and maize.  From several locations around the ceremonial area, the Thirteen Towers are the dominant feature in the horizon and could be used as solar horizon markers, but one building is of particular interest.  It is a small, isolated structure in the middle of a large, open space.  Only the incomplete outline of a rectangular room, 6 m wide, is preserved.  Its position in relation to the towers mirrors almost exactly the western observing point: the two lie on the same east-west line, have similar elevation, and are at the same distance from the Thirteen Towers.  When viewed from inside this building, the spread of the towers forms an artificial horizon as well. Like the corridor leading to the western observing point on the opposite side of the towers, we hypothesize that this room contained an eastern observing point, though its exact position cannot be known, due to poor preservation, with the same certainty as that of the western observing point.

From this eastern observing point, the southernmost tower (Tower 13) would not have been visible, and the top of Tower 12 would only just have been visible (it is only partially visible now due to its ruinous condition).  From here, the December solstice Sun set behind the left side of the southernmost visible tower (Tower 12), whereas the June solstice Sun sets directly to the right of the northernmost tower (Tower 1).

From each observing point, once the Sun had begun to move appreciably away from either of its extreme rising positions a few days after each solstice, the towers and gaps would have provided a means to track the progress of the Sun up and down this artificial horizon to within an accuracy of two or three days.

Justification of Outstanding Universal Value

The Chankillo Astronomical Complex is the earliest example known to date in the Americas of a monument devoted to an astronomical function (Ghezzi & Ruggles 2007).  The carefully chosen location –in a place of exceptional natural beauty, with an appropriately low natural horizon for sky observation—, the construction of an artificial horizon, and the precise design of the observing points and markers are an extraordinary example of the cultural transformation of a natural landscape, and of the vital role of astronomical knowledge within ancient civilizations.

At this site we find direct indications of all solstitial rising and setting points, together with the means to observe and uniquely identify the time of the year, with a precision of 2-3 days, by observing sunrises or sunsets against the Thirteen Towers. This is an example of landscape timekeeping; a practice of ancient civilizations that used visible natural or cultural features to keep track of the cyclical passage of celestial bodies, and represents a masterpiece of human creative genius.

The Chankillo solar observation device represents an early developmental stage of native astronomy in the Americas (Aveni 2008).  In this part of the world, there is a long-standing relationship between humanity and the sky.  Ancient Andean peoples, like other ancient civilizations, often structured their actions within a particular view and understanding of the landscape, including the sky.  Chankillo reveals a great deal about the ways people, before the advent of written records, perceived, understood, and attempted to order and control the world they inhabited through astronomy.

Like many other ancient civilizations, Andean peoples imprinted their particular worldview onto their sacred buildings. At Chankillo, they incorporated specific features for astronomical observation and timekeeping. Thus, in the category of architectural monuments devoted to astronomical functions, Chankillo is unique and exceptional, bearing testimony to a cultural tradition that has disappeared.

Criteria (i): The Chankillo Astronomical Complex is a masterful example of landscape timekeeping, a practice of ancient civilizations worldwide, which used visible natural or cultural features.  At Chankillo, we find direct indications of all four solstitial rising and setting points, together with means to observe and uniquely identify the time of the year, with a precision of 2-3 days, by observing sunrises or sunsets against the intervening towers. In this sense, the astronomical facilities at this site represent a masterpiece of human creative genius.

Criteria (iii): Ancient Andean peoples often structured their actions within a particular view and understanding of the landscape, including the sky. The Chankillo Astronomical Complex reveals a great deal about the ways in which, in this part of the world, people before the advent of written records perceived, understood, and attempted to order and control the world they inhabited through astronomy.  Therefore, Chankillo and its astronomical installations bear a unique and exceptional testimony to a cultural tradition that has disappeared.

Criteria (iv): The Chankillo Astronomical Complex is a very particular type of building representing an early stage in the development of native astronomy in the Americas.  In this part of the world, there is a long-standing relationship between humanity and the sky, and ancient Andean peoples, like other American civilizations, imprinted their particular worldview onto their sacred buildings. In some cases, they incorporated in them specific features for timekeeping. Within the category of architectural monuments devoted to an astronomical function, Chankillo truly stands out.

Statements of authenticity and/or integrity

Chankillo Astronomical Complex is interpreted as a great ceremonial complex devoted to a solar cult, by means of a ceremonial calendar structured through precise astronomical observation of the alignments between the Thirteen Towers and observing points. The comprehensive research carried out at the site testifies to the authenticity and integrity of the constructions that make up the fabric on which these exceptional values rest. Nevertheless, these features are very fragile and require urgent conservation.

The authenticity of Chankillo Astronomical Complex is confirmed by existing archaeological evidence, which has been found in relatively good state of preservation.  There are direct indications of the solstitial and equinoctial rising and setting points, together with the means to observe and uniquely identify a date with a precision of 2-3 days, by observing sunrises/sunsets against the towers.  No major conservation or restoration projects has been attempted to date on the features bearing the exceptional values of Chankillo.  However, plans for a conservation/restoration project at the Fortified Temple in Sector 1 were drafted in the 1960s by Peruvian conservator Victor Pimentel and plans for an intervention of the entire site are being readied by the current Chankillo Archaeological Project.

The integrity of the constructions that make up the fabric on which Chankillo´s exceptional values rest is secured through a protected zone, ratified by a ministerial resolution from the Ministry of Culture, which has been defined through comprehensive research and includes elements of the landscape which could have been part of the astronomical complex.  Nevertheless, these features are very fragile and require urgent conservation measures. Further research is needed to characterize the nature of occupations at Chankillo to the east and north of the Thirteen Towers, and assess their integrity. Similarly, more studies are required to define the extent to which the horizon visible to the east from the Fortified Temple and the Thirteen Towers contained natural features that could also be used for astronomical purposes (Ghezzi & Ruggles 2011). This proposed cultural landscape is outside of the current zone under legal protection, and its extent remains to be defined.

Comparison with other similar properties

Monumental remains from pre-literate cultures can exhibit relationships to the sky in many different ways, but one of the most extensively investigated is where they incorporate structural alignments upon the horizon rising and setting points of celestial objects. A problem in assessing the significance of such alignments is to establish beyond reasonable doubt, in the absence of corroborating cultural evidence other than that available from the archaeological record itself, that such alignments were likely to have been intentional.  There always exists the possibility that any oriented structure could align purely fortuitously upon an apparently significant rising or setting point.

Alignments upon the rising or setting positions of stars, while possibly commonplace in prehistory, can only rarely be demonstrated in the absence of corroborating historical evidence. This is because of the large number of bright stars in the sky and the fact that, owing to precession of the equinoxes, their rising and setting positions shift significantly over the centuries (There are further problems owing to atmospheric effects such as extinction: see Ruggles 1999: 52).  This means that there is a high chance of being able to fit an astronomical explanation to any random direction by choosing a suitable star and a suitable date within the chronological range suggested by the archaeological evidence.  Claims to have dated sites astronomically based on stellar alignments are especially suspect, being usually based on dangerously circular arguments.

The rising and setting positions of the sun, moon and planets, while changing on a day-to-day basis, are not affected by precession, although they are subject to a much smaller systematic change on a timescale of millennia.  Apart from this, the sun’s motions are essentially straightforward (it swings steadily to and for over an annual cycle between limits at the two solstices), the moon’s are more complex (moonrise and moonset move up and down the horizon once each month, with the limits themselves varying over a cycle of 18.6 years), and those of the planets more complex still.  Since simplicity in the motions of a heavenly body means that there are relatively few plausible “targets,” it is primarily solar, and to a lesser extent lunar alignments, which can be established with the greatest confidence from the disposition of archaeological remains.

There are two ways of establishing the likely intentionality of a putative astronomical alignment: statistical and contextual (Ruggles 2000). The statistical argument is only applicable where there exists a group of similar monuments that can be shown to be consistently aligned, when paying due care and attention to the fair selection of evidence.  Excellent examples exist from the Neolithic in western Europe, such as the 177 seven-stone antas of central Portugal and western Spain which are aligned without exception upon sunrise (Hoskin 2001: 95–100) and the 58 recumbent stone circles of eastern Scotland, which are consistently aligned in relation to the midsummer moon (Ruggles 1999: 91–99).  No sites such as these are yet included on the World Heritage List, since no individual site in either group stands out as particularly significant, although they are candidates for serial nomination.

The contextual approach is more subjective but has two distinct advantages: 1) it can help identify “one-off” instances of deliberate astronomical orientation; and 2) it can help to address questions of motive and meaning.  Thus the Neolithic passage grave at Newgrange in Ireland, part of the Bend of the Boyne World Heritage Site (#659), the presence of the famous “roof-box” argues that the alignment of the passage upon winter solstice sunrise was intentional; and the fact that the primary purpose of the site was as a tomb argues that the solstitial alignment expressed some perceived connection between the sun and seasonal cycles and death and ancestors: this was clearly not an “observatory” or calendrical device (Ruggles 1999: 12–19). On the other hand, the solstitial orientation of the Dacian fortress of Sarmizegetusa Regia in Romania, part of the Dacian Fortresses of the Orastie Mountains World Heritage Site (#906), was “ideal” rather than practical.  It assumes a flat rather than a mountainous horizon; if deliberate, it does not result from direct observations of sunrise but reflects the influence of geometrical concepts from Hellenistic Greece (Ruggles 2005: 370–372).

Unfortunately, at many sites where numerous putative solar and/or lunar alignments have been identified, providing the basis on which the site has been claimed to be an ancient astronomical “observatory,” the evidence has turned out to be archaeologically and statistically unsubstantial.  This includes Stonehenge in England, part of the Stonehenge, Avebury and Associated Sites World Heritage Site (#373) (Ruggles 1999: 35–41), where only the solstitial alignment of the main axis of the Phase 3 (stone) monument is securely established, being repeated at several similar contemporary monuments in the immediate vicinity (Ruggles 2007).

At many sites around the world, including all of those above mentioned, their significance in relation to the sky is evident through a single astronomical alignment. In contrast, the towers at Chankillo Astronomical Complex span (to within a couple of degrees) the entire solar rising and setting arcs as seen from two observing points, each clearly defined by a unique structure with no other apparent purpose.  Thus, we are not selecting putative astronomical targets from innumerable possibilities, but seeing direct indications of all four solstitial rising and setting points together with the means to observe and uniquely identify every other day in the year by observing sunrise or sunset against the intervening towers (Ghezzi & Ruggles 2007).  The broad significance across cultures of the solstices as astronomical “targets” is self-evident and widely attested.  In this sense, Chankillo Astronomical Complex is unique, not just in Peru or in the Americas but in the entire world.

It is clear from a range of evidence at Chankillo that direct observations were made of the annual movement of the rising or setting sun along the horizon for the purposes of regulating seasonal events such as religious festivals, and very possibly for maintaining a seasonal calendar. In this sense, the site can truly be referred to as an “observatory” despite the ethnocentric connotations this term has acquired in recent years.  In this sense, it even stands out from the so-called Group E Structures, one of the most significant sets of monuments in the Americas with regard to their relationship to the motions of the sun, and an obvious candidate for a serial nomination to the World Heritage List on the ground of their relationship to astronomy.  These fifty structures in the Mayan heartlands of the Peten, Guatemala, are named from their similarity to the structure known as Group E at the city of Uaxactun, which incorporates architectural alignments upon both solstices and the equinoxes, and has become renowned as a solar observatory.  However, the remaining Group E structures, although broadly contemporaneous and similar in form, do not generally exhibit the same precise alignments as at Uaxactun.  Furthermore, the Uaxactun structure was itself modified later, which had the effect of rendering it useless for precise observations. A possible interpretation is that, while some of the Group E structures incorporated functional solar alignments, others were “non-functioning” replicas whose importance—even in so far as this related to calendric rituals and ceremonials—did not need to be reinforced by actual observations of the sun.