University City, the main campus of UNAM, the National Autonomous University of Mexico, is a World Heritage Site, and it was founded in 1551, just four months after the oldest university in the Americas was founded in Peru. It is autonomous, meaning free to teach without government interference, although the PRI government did kill hundreds of students in 1968, during the Tlatelolco massacre. The faculty and alumni include all Mexican Nobel winners to date. The north face of the 10 story Central Library (above) is covered with Aztec mural mosaics by Juan O’Gorman, friend of Diego Rivera.