Sacsayhuamán or Saksaywaman is a citadel on the northern outskirts of the city of Cusco, Peru, the historic capital of the Inca Empire. The site is at an altitude of 3,701 metres. The complex was built by the Incas in the 15th century, particularly under Sapa Inca Pachacuti and his successors. Dry stone walls constructed of huge stones were built on the site, with the workers carefully cutting the boulders to fit them together tightly without mortar.