Sacsahuamán or Sacsayhuaman: An immense fortified Inca complex, built as an adjunct to the Incan capital at Cuzco, Peru, and begun some time after 1438. Thought to have functioned as a storage center and military garrison in peacetime, it was used as a safe haven for Cuzco residents in times of danger. Its north-facing limestone walls are Cyclopean and the remains of round towers are still visible. They are built on a zigzag sawtooth plan and the interior structures are built on three rising terraces and include storage and dwelling places, a reservoir and a conduit supply system. It is said to have been constructed over a period of 80 years with the labor of 20,000 Incans.