Whats really fascinating about Machu Picchu is that it was build using only hand tools, by people who didn’t even have the wheel. The stones that make up the walls of the temples fit together so perfectly that you can’t push a knife blade trough. The Incas didn’t rely on mortar to hold together the stones instead they at fitted together like a jigsaw, finely shaped into place. it’s belived that they used a copper saw with sand to file down the rock. And then poured water into the crack. Being at high altitude the water would freeze at night expanding and deeping the crack. thereby breaking the stone.
Another interesting feature of Machu Picchu is that no matter which season it is. The water flow to the fountains remain constant. It’s stilling working to this day, even after being abandoned for 500 years.