Just outside Cuzco is a fortress that was built to defend the city. It is called SAQSAYWAMAN It supposedly had 10,000 Incan warriors there.
For the last 80 or so years the people of Cuzco have been removing the stones to built houses, etc. and before that the Spanish destroyed as much as they could. so only a small portion of the fortress is left. but look what is left and try to imagine how big this megalith was.
some of those stones are over 20 feet high, weight 130 tons or more.