Sacsayhuamán

A massive Inca citadel on the northern outskirts of Cusco, Peru, built under Emperor Pachacuti in the 15th century using approximately 20,000 laborers. The fortress features three concentric zigzag walls stretching over 540 metres, built from precisely interlocking polygonal stone blocks -- some exceeding 100 tons -- fitted without mortar. Beyond military defense, Sacsayhuaman served as a religious center with temples to the sun god Inti and a major storage depot. Part of the UNESCO World Heritage City of Cusco, it hosts the annual Inti Raymi festival.