Cusco city in 1535. Remains of the palace of the Incas, Qurikancha (the Temple of the Sun) and the Temple of the Virgins of the Sun still stand. Inca buildings and foundations in some cases proved to be stronger than the foundations built in present-day Peru. Among the most noteworthy Spanish colonial buildings of the city is the Cathedral of Santo Domingo, Cusco. The major nearby Inca sites are Pachacuti's presumed winter home, Machu Picchu, which can be reached on foot by the Inca Trail to Machu Picchu or by train; and the "fortress" at Ollantaytambo. Less-visited ruins include: Incahuasi, the
Machu Picchu prevent it from running down the mountain. Similar layering protected the large city center from flooding. Multiple canals and reserves provide water throughout the city that could be supplied to the terraces for irrigation and to prevent erosion and flooding. The Incas never used wheels in a practical way, although their use in toys shows that they knew the principle. The use of wheels in engineering may have been limited due to the lack of strong draft animals, steep terrain and dense vegetation. The approach to moving and placing the enormous stones remains uncertain, probably involving hundreds of men to