Sacsayhuaman, Cusco, Peru
Sacsayhuaman is a citadel on the northern outskirts of the city of Cusco, Peru, and the historic capital of the Inca Empire. It was first built by the Killke culture in the 1100s and they occupied the area from the 900s.
The construction of Sacsayhuaman remains a mystery and researchers are still looking at how it was created. This historic place looks like the game Tetris and the architect John McCauley believes that the small stones were carried by the workers, and the heavy ones were dragged on a sled.