Sacsayhuaman
An imposing example of Inca military architecture, the fortress of Sacsayhuaman was built using large slabs of granite to safeguard the city from attack by Antis, or invading forces from the East. Sacsayhuaman ("satisfied falcon" in Quechua) is made up of three large terraces which overlap in a zigzag formation surrounded by enormous stone ramparts of up to 300 meters in length. Its elevation and proximity to Cusco, as well as the dimensions of the stones -up to 5 meters high and weighing up to 350 tons- made Sacsayhuaman a quarry for certain structures in colonial Cusco.
Kenko and Puca Pucara
Kenko is a ritual site built on a sole outcrop of limestone, with underground galleries and a semicircular amphitheatre. Puca Pucara (in Quechua, "red fortress"), was a military installation made up of stairways, terraces and large walls which once formed part of the capital's defence system. Both structures are part of the archaeological circuit near the city of Cusco.
Tampumachay
Also known as the "Baños del Inca" or the Inca baths, Tampumachay was apparently a site dedicated to the worship of water and a resting place for the Inca monarch. Among its most notable features are its system of aqueducts, canals and cascades carved in stone, designed to channel water flowing from a nearby spring. According to experts, Tampumachay was also a kind of royal garden, abounding in ornamental vegetation and fed by an intricate network of canals.
Source: PromPerú (Comission for the Promotion of Peru).