Sacsayhuaman is an large megalithic site in Peru that is a UNESCO World Heritage Site.  It is an old Inca fortress that is just outside Cusco, overlooking the town.

It was excavated in the 1930s.  In 2008, more ruins from the fortress complex were found and are still being evaluated.

It consists of enormous rocks cut expertly to fit together into nearly 20-foot tall walls and is very impressive as the stones have no mortar, yet you can’t put a piece of paper between them.

 

There used to be more to the fortress complex, but the Spanish took all of the smaller rocks to build houses, churches, and public buildings in Cusco.