|A wall inside the temple
Notice how well the stones fit together.
One of the things that the Incas did not have was mortar. Mortar is traditionally used for constructing buildings of stone or brick. Mortar binds the stones together so they cannot be moved. The Inca buildings were so perfectly constructed that not only do many of them still exist today, but they have very little damage. In fact some of them were so tightly constructed that you cannot today even slide a piece of paper between the stones. And remember the Incas didn't have the wheel, so they had to drag or carry these stones.