Chankillo - Prehistoric Astronomical Observatory in Peru at 300 BC

What Did the 13 Towers of Chankillo Track for Ancient Peruvians?

Chankillo at the June Solstice Sunrise, 2003
The rise of the sun between Tower 1 and Cerro Mucho Malo at the June solstice, 2003, viewed from the western solar observatory. The sunrise position at the solstice has shifted to the right approximately 0.3° from year 300 BC. Image courtesy Ivan Ghezzi

Chankillo (spelled Chanquillo on some websites but very rarely in the published literature) is an Early Horizon Chavín culture ceremonial center and solar observatory located within an area of rock outcrops and sand ramps in the Casma-Sechin river valley of arid coastal Peru. Chankillo was built between about 2350–2150 calendar years ago (cal BP), or between about 300-100 BC. Recent archaeoastronomical nvestigations indicate that Chankillo was one of the first, if not the first solar observatory built in South America, created to observe the movement of the sun throughout the year.

Structures at Chankillo were built of shaped stone and mortared walls, and they include a ceremonial-civic area with buildings, a large open plaza, storage facilities, and several smaller scattered buildings, all within an area of about 4 square kilometers (~1,000 acres). A 300-meter (1,000-foot) long oval hilltop structure with massive walls, restricted gates and parapets is also an important component of Chankillo.

Thirteen Towers at Chankillo

Chankillo's astronomical feature includes an array of thirteen stone towers arranged in a line like the teeth of a comb along the ridge of a low hill, located between the civic/ceremonial center and the hilltop structure. The line runs due north/south, but the southern-most towers are slightly skewed to the southwest.

The towers vary in size, from 75 to 125 m (246-410 ft) square and 2-6 m (6.5-20 ft) in height, and they vary in plan, from rectangular to rhomboidal.

However, when they were built they were all flat on the top, and they are regularly spaced, at intervals between 4.7 and 5.1 m (15.4-16.7 ft). Together, the height of the towers, the regular spacing and the flat tops make an artificial horizon raised above the ridge. Each tower has a pair of narrow (1.3-1.5 m or 4.2-4.9 ft) inset staircases leading to the summits.

As observed from two viewing platforms, the spread of the towers corresponds closely to the range of movement between the rising and setting positions of the sun about the year ~300 BC, with the December solstice visible at the tower on the northern end (Tower 1), and June's solstice at the southern (Tower 13). See Ghezzi and Ruggles (2011) and Malville (2011) for details.

Watching the Sunrise

Two viewing platforms are present at Chankillo, for watching sunrise and sunset. The western platform is within a restricted passageway in a ceremonial building near the towers; the eastern is in a tiny isolated room in the plaza. A large ceremonial plaza to the east was clearly intended for use by large groups of people, while the small viewing platforms were likely reserved for one or two elite individuals. From the viewing platforms, the towers mark the range of the sun in the sky, from solstice to solstice.

Alterations of the landscape for tracking the movements of the sun and moon are known in South America; it has been suggested as one possible purpose for the Inca ceque system. Spanish chroniclers reported that there were 16 'sun pillars' set around the perimeter of the Inca capital of Cusco at the time of the conquest, although none of them exist today.

Fortress Temple

The 300-m (1000-ft) long fortress temple at Chankillo includes three buildings, two circular and one rectangular, enclosed by three massive concentric walls. The innermost wall acts as a retaining wall, supporting the terrace on which the buildings were built. The outer walls stand 8 m (26 ft) high in places and are 6.5 m (21 ft) thick: these walls consisted of two parallel walls with an interior rubble core. The exteriors of these walls were painted tan, yellow and white, and are sometimes textured with finger impressions.

Five gateways on the outer-most wall and three more on the middle wall have constructed baffles, walls which limit access and view of the interior, creating a maze-like effect for the temple. The remnants of three parapets are on the innermost wall.

This massive fortified structure has been interpreted as many things in the literature, including a fort, a redoubt, a temple, and a ceremonial center.

Ghezzi (2006) argues that the construction method, coupled with other evidence at the site, implies the this group of buildings was a fortified temple.


Artifacts associated with the buildings and plazas suggest a ceremonial function with recurring feasts at Chankillo. Several warrior figurines holding weapons and in a combat position have been recovered from the site, as well as ceramic panpipes, and serving vessels.

Thousands of river-rolled spherical cobbles litter the hillside next to the fortress, which had to have been brought from the riverbed some 2 kilometers (1 mile) away. Scholars believe these were slingstones, missiles thrown from the fort at an (ceremonial or real) enemy.

Abundant maize and Spondylus shellfish remains have been found inside of rooms built to store chicha corn beer.


Chankillo was first investigated by Julio C. Tello. Excavations at Chankillo have been conducted by a Yale University expedition, led by Ivan Ghezzi.

Archaeoastronomical research was conducted by a joint expedition with Clive Ruggles, of the University of Leicester.


More photographs of the site have been passed along to us by investigator Ivan Ghezzi, and presented in the Photos of Chankillo page.

This article is a part of the guide to Ancient Observatories, and the Dictionary of Archaeology.

Ghezzi I. 2006. Religious Warfare at Chankillo. In: Isbell W, and Silverman H, editors. Andean Archaeology III: Springer US. p 67-84.

Ghezzi I, and Ruggles C. 2006. Las trece torres de Chankillo: arqueoastronomía y organización social en el primer observatorio solar de América. Boletin de Arqueoligía PUCP 10:215-235.

Ghezzi I, and Ruggles C. 2007. Chankillo: A 2300-Year-Old Solar Observatory in Coastal Peru. Science 315:1239-1243.

Ghezzi I, and Ruggles CLN. 2011. The social and ritual context of horizon astronomical observations at Chankillo.Proceedings of the International Astronomical Union 7(Symposium S278):144-153. doi:10.1017/S1743921311012567

Malville JM. 2011. Astronomy and ceremony at Chankillo: an Andean perspective. Proceedings of the International Astronomical Union 7(Symposium S278):154-161. doi:10.1017/S1743921311012579