People don't seem to know what this structure was, high in the mountains above Samaipata. Some say it was a fortress of some sort. Others claim it was a temple, and that the various little troughs that run around the old foundations were for making the blood flowing from the sacrifices flow away from the main traffic corridors.
It is thought to be the worlds largest carved stone.
It has now been declared a world heritage site, and therefore supposedly has a lot more tourist activity now than when I visited in 2001. At that time only two or three other people or groups of people were visiting, and one lone vendor of local crafts sat at a lonely post selling a small amount of hand made goods.
At that time, the road to get here was a nearly unmarked unpaved, and nearly ungraveled road. Today, I have been told that it is far more developed.