Note how closely the rock has been made to fit together.
Walls of the fortress.
The angles of the walls made it difficult for the attackers to overcome the fortress.
Saksaywaman, Sasawaman, Saksawaman, Sasaywaman, Saqsaywaman[2] or Saksaq Waman (Quechua waman falcon[3] or variable hawk,[4] hispanicized spellings Sacsayhuamán, Sacsayhuaman, Sacsahuaman, Saxahuaman and others) is a walled complex on the northern outskirts of the city of Cusco, Peru, the former capital of the Inca Empire. Like many Inca constructions, the complex is made of large polished dry stone walls, with boulders carefully cut to fit together tightly without mortar.