Sacsahuamán (säksäwämänˈ) [key], 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.