Towards the first decades of the thirteenth century, when the Tawantinsuyu started its expansion, it was necessary to give the capital the required characteristics of an imperial city. It was the Inca Pachacútec who started this exceptional reform and who commanded that the most magnificent buildings, like the Korikancha, the Acllahuasi, and the Yachayhuasi, be constructed, using an enormous amount of manpower. The historians calculate that more than 50,000 people worked on the construction. Pachacútec reconfigured the city, diverted the Huatanay River from its original course that passed through it, and divided Cusco into twelve neighborhoods, giving it the form of a puma.
The Spanish founding of Cusco, on March 23, 1534, brought the second great transformation to the city. Almost every building was destroyed and sacked, and on top of their groundwork were built Renaissance mansions and catholic churches. Almost overnight, Cusco became a mixed city that forged part of the most important cultural expressions in America. Along its cobble stoned streets lived the remaining Incan nobility, the Spanish, the Creoles and half bloods, and the common, indigenous people.
The silver trade from the Potosí mines in Bolivia made Cusco the most important crossroads between Lima and the rich sources of the Peru Viceroyalty. Soon the church established roots there and founded churches of all styles and trends. Cusco was the site of the first diocese in South America, and the presence of the religious orders stimulated a cultural apogee that resulted in the creation of its own school of painting as well as the founding of the University of San Antonio Abad in 1669.