Puma Punku
Puma Punku is an ancient ruin found in Bolivia that dates back to the 6th century CE. It stands out for a number of reasons, both for its history and for its construction. The site features stonework that is unlike anything of the period. Precise cuts were made to not only add detail to the ruins but also to precisely fit the massive stone blocks together. The blocks were cut at exact angles so that they would fit together like a puzzle and not require the use of mortar of any kind. Even centuries later the rocks fit so tightly together that not even a razor blade can slip between them.
The intricate carvings on the rocks with straight lines and angles also stand out. There are no chisel marks of any kind and trying to recreate these cuts with the tools known to be available at the time has yet to be accomplished. Moving the rocks to the site was even a feat as some weighed as much as 100 tons and were moved from a quarry 60 miles from the site. The ruins exist above the tree line so there were not even any trees to use to make rollers to move the massive blocks.
There is even contention over the dating of the ruins. Some put the ruins at over 10,000 years old, despite the carbon dating. When the Incas conquered the region in the 15th century, they incorporated Puma Punku and the rest of Tiwanku city into their empire. Puma Punku became a huge part of the Incan culture because it was believed to be the place where Viracocha created the ancestral people of all ethnicities and sent them out to populate the world.
While it is not known for certain, it is theorized that Puma Punku served as a spiritual and religious center. At its peak Puma Punku and Tiwanaku city supported 400,000 people and had a very extensive infrastructure. By 1000 CE the culture abruptly ended for reasons that are still unknown today.