Architecture was by far the most important of the Inca arts, with textiles reflecting motifs that were at their height in architecture. The main example is the capital city of Cusco. The site of Machu Picchu was constructed by Inca engineers. The stone temples constructed by the Inca used a mortarless construction that fit together so well that a knife could not be fitted through the stonework.
This was a process first used on a large scale by the Pucara (ca. 300 BC–AD 300) peoples to the south in Lake Titicaca, and later in the great city of Tiwanaku (ca. AD 400–1100) in present-day Bolivia. The rocks used in construction were sculpted to fit together exactly by repeatedly lowering a rock onto another and carving away any sections on the lower rock where the dust was compressed. The tight fit and the concavity on the lower rocks made them extraordinarily stable.