El Fuerte de Samaipata

This UNESCO World Heritage site was a holy place and ceremonial site of the local pre-Inca and Inca civilizations, and was used further by the Spanish until the new town of Samaipata was built. There are ruins of all three eras here. The centerpiece, however, is the huge, carved ceremonial rock. There's not too much to see in terms of buildings or statues, but if you're interested in the ancient cultures and read all the signs on the site or hire a guide, then it makes for a good day trip (on foot) or half-day trip (by car/taxi) from Samaipata. To go there on foot, head east along the highway (direction Santa Cruz) for 3 km until the road going uphill to the right, where a sign points you to 'El Fuerte de Samaipata'. Follow this road (with almost no traffic) for about 6 km uphill, and you end up directly at the entrance.