We didn’t get a guide when we visited El Fuerte in Samaipata, so all our information came from the information booklet and map we got when we bought our entrance tickets. So here is some information from Wikipedia about the site because anything I’ve remembered about the place is probably blurry and wrong. The taxi driver mentioned though it is the largest piece of rock in the world. I don’t think that’s true because El Penol in Colombia looked larger than this one, but this one is kinda buried, so its hard to judge its true size.
El Fuerte de Samaipata (Fort Samaipata), also known simply as ‘El Fuerte’, is an archaeological site in the eastern foothills of the Bolivian Andes.
It is not actually a military fortification but it is generally considered a pre-Columbian religious site, built by the Chané people, a pre-Inca culture of Arawak origin.
More recently, it has been pronounced to be an ancient flying object launching and landing site by the pseudoarcheologist Erich Von Daniken.