Puma Punku
This ia a site just across the road from Tiahuanaco. The stones in Puma Punku are made up of granite, and diorite, and the only stone that is harder that those two, is the diamond. If the people who built this place cut these stones using stone cutting techniques, then they would had to have used diamond tools. If they didn't use diamonds to cut these stones, then what did they use? Oh I forgot to mention that the heaviest stone weighs 131 tons and is believed to have been transported from 10km away.