Sacsahuamán, stronghold of the Incas outside Cuzco, Peru. Built in the 15th cent., Sacsahuamán is an imposing terraced fortress more than one third of a mile long; it is a masterpiece of stone construction. Cyclopean blocks (one is 38 ft/11.6 m long; 18 ft/5.5 m high; and 6 ft/1.8 m thick) were brought from some distance over rugged terrain without wheeled vehicles and then were fitted precisely. It was captured by the Spanish garrison besieged (1536-37) in Cuzco by Manco Capac. The loss hastened the defeat of the Native Americans.