An engineered mountain
Positioned at an altitude of 3,000 meters, the Kuelap Fortress is a massive limestone construction of the Chachapoya culture. The main site occupies a ridge 584 meters long and about 110 meters at its widest point. Its construction began around the 6th century AD, hundreds of years before the Inca citadel of Machu Picchu. The perimeter walls reach heights of up to 20 meters and are so immense that their total stone volume is greater than that of the Great Pyramid of Giza in Egypt. To build the two primary walls alone required over 100,000 blocks of carved rock, weighing more than 10,000 tons.
Inside the main enclosure are the remains of more than 420 circular stone buildings, a signature of Chachapoya architecture. The fortress is divided into two main levels, the Lower Town and the Upper Town, with the latter housing about 80 structures and thought to be for the city's elite. Access to the citadel is restricted to three narrow, funnel-like entryways. These passages constrict to a width that permits only single-file entry, a clear defensive design. The entire complex demonstrates advanced engineering, including a sophisticated drainage system.
The science of a lost culture
Archaeological science at Kuelap reveals details about the Chachapoya people and their eventual demise. Bioarchaeological analysis of human remains found within the walls points to secondary burial practices, a custom in pre-Columbian Peru. At its peak, the city may have supported a population of around 3,000 people. The Inca conquered the Chachapoya around 1475 AD, and remains of rectangular Inca buildings have been found inside Kuelap, evidence of their occupation.
A prominent structure in the Lower Town is the "Tintero," or inkwell. This 5.5-meter-high building is shaped like an inverted cone and contains a bottle-shaped inner chamber. Evidence suggests it functioned as a solar observatory. Another important structure, the Torreón, or tower, sits at the highest point of the fortress and was a watchtower; archaeologists discovered a cache of 2,500 sling stones nearby.
In April 2022, a section of the southern perimeter wall collapsed following unusually heavy rainfall. Scientific analysis using satellite radar and thermal drones determined that climate change, which caused the intense precipitation between 2018 and 2022, was a factor in the collapse. This event has prompted new conservation and research efforts using technologies like LiDAR to fully map the site in 3D.