<P> Incan architecture is the most significant pre-Columbian architecture in South America . The Incas inherited an architectural legacy from Tiwanaku, founded in the 2nd century B.C.E. in present - day Bolivia . The capital of the Inca empire, Cuzco, still contains many fine examples of Inca architecture, although many walls of Inca masonry have been incorporated into Spanish Colonial structures . The famous royal estate of Machu Picchu (Machu Pikchu) is a surviving example of Inca architecture . Other significant sites include Sacsayhuamán and Ollantaytambo . The Incas also developed an extensive road system spanning most of the western length of the continent . </P> <P> Inca buildings were made out of fieldstones or semi-worked stone blocks and dirt set in mortar; adobe walls were also quite common, usually laid over stone foundations . The material used in the Inca buildings depended on the region, for instance, in the coast they used large rectangular adobe blocks while in the Andes they used local stones . The most common shape in Inca architecture was the rectangular building without any internal walls and roofed with wooden beams and thatch . There were several variations of this basic design, including gabled roofs, rooms with one or two of the long sides opened and rooms that shared a long wall . Rectangular buildings were used for quite different functions in almost all Inca buildings, from humble houses to palaces and temples . Even so, there are some examples of curved walls on Inca buildings, mostly in regions outside the central area of the empire . Two - story buildings were infrequent; when they were built the second floor was accessed from the outside via a stairway or high terrain rather than from the first floor . Wall apertures, including doors, niches and windows, usually had a trapezoidal shape; they could be fitted with double or triple jambs as a form of ornamentation . Other kinds of decoration were scarce; some walls were painted or adorned with metal plaques, in rare cases walls were sculpted with small animals or geometric patterns . </P> <P> The most common composite form in Inca architecture was the kancha, a rectangular enclosure housing three or more rectangular buildings placed symmetrically around a central courtyard . Kancha units served widely different purposes as they formed the basis of simple dwellings as well as of temples and palaces; furthermore, several kancha could be grouped together to form blocks in Inca settlements . A testimony of the importance of these compounds in Inca architecture is that the central part of the Inca capital of Cusco consisted of large kancha, including Qurikancha and the Inca palaces . The best preserved examples of kancha are found at Ollantaytambo, an Inca settlement located along the Urubamba River . </P> <P> Inca architecture is widely known for its fine masonry, which features precisely cut and shaped stones closely fitted without mortar ("dry"). However, despite this fame, most Inca buildings were actually made out of fieldstone and adobe as described above . In the 1940s, American archaeologist John H. Rowe classified Inca fine masonry in two types: coursed, which features rectangular shaped stones, and polygonal, which features blocks of irregular shape . Forty years later, Peruvian architect Santiago Agurto established four subtypes by dividing the categories identified by Rowe: </P>

Who laid the foundations of the inca empire