This is How They Built the Inca Stone Walls
The perfectionist Inca stonework is remarkable. This is because they laid the stones so precisely that the use of mortar to hold them together was not necessary. In fact, so perfectly the stones fit, that a piece of paper would not fit between them.
The Incas were certainly skilled stonemasons. They used granite or limestone to build their cities, these materials were available locally. To cut the rocks they used stones, metal tools made of bronze or copper, pieces of wood and water.
Through the dry fitted masonry techniques of caninacukpirca, the Incas shaped their stone to conceal natural outcrops, fit tight crevices, and ultimately incorporate the landscape into their infrastructure. The Inca also used natural bedrock as their structural foundations (to help keep the buildings stable).