The most interesting ruins near Puno  are surely Sillustani (6 a.m.–dark, US$4), which are halfway between Puno and Juliaca  at the end of a 14-kilometer detour off the highway. The site consists of more than a dozen stone tombs, or chulpas, up on a bluff over Lago Umayo.
They were mostly built by the Colla, a highland people conquered by the Inca in the 15th century and for whom this quarter of the Inca empire (Collasuyo) was named. The Colla were stone craftsmen and built gravity-defying towers that widen as they go up. Whether they built the towers this way to show off their masonry virtuosity, or to stymie grave robbers is unknown, but the Inca continued the tradition.
Over time, even the perfectly fitted granite stones of the Incas have spilled onto the surrounding ground, exposing the tower’s adobe-filled interior, which was long ago ransacked by looters.
The drive in passes the stone homes of llama herders, which are decorated with arches and stone bands. Near the chulpas, don’t miss the waru waru, an ingenious farming technology that was developed around Lake Titicaca  during the Tiwanaku empire. These raised earth platforms are surrounded by a thin pool of water that absorbs the sun’s energy during the day and re-radiates it at night, protecting the potatoes and other crops from frost.
To arrive, take any bus heading north from Juliaca  (many leave from Simón Bolívar) and ask to be dropped off at the Sillustani turnoff (US$0.30, 20 km). Taxis wait at the turnoff and charge US$0.50 to take travelers the remaining 14 kilometers to the ruins.