DE-948671, sent by Claus.
"The ensemble of buildings, sports facilities and open spaces of the Central University City Campus of the Universidad Nacional Autónoma de México (UNAM), was built from 1949 to 1952 by more than 60 architects, engineers and artists who were involved in the project. As a result, the campus constitutes a unique example of 20th-century modernism integrating urbanism, architecture, engineering, landscape design and fine arts with references to local traditions, especially to Mexico’s pre-Hispanic past. The ensemble embodies social and cultural values of universal significance and is one of the most significant icons of modernity in Latin America." - in: http://whc.unesco.org/en/list/1250 It was declared a World Heritage Site in 2007.
Information about the solar, Toltec, and Maya calendars is carefully built into el Castillo. Each stairway has exactly 91 steps, times four is 364 plus the top platform equals 365, the days in the solar calendar. The pyramid has 52 panels in the nine terraces; 52 is the number of years in the Toltec cycle. Each of the nine terraced steps are divided in two: 18 for the months in the yearly Maya calendar. Most impressively, though, is not the numbers game, but the fact that on the autumnal and vernal equinoxes, the sun shining on the platform edges forms shadows on the balustrades of the north face that look like a writhing rattle snake." - in: http://archaeology.about.com/od/archaeologic7/ig/Chichen-Itza/El-Castillo.htm
Today "El Castillo" is one of the most recognized and widely visited pre-Columbian structures in present-day Mexico.
As one of the buildings the Chichen Itza archaeological site, El Castillo, also known as the Temple of Kukulkan, is on the World Heritage List since 1988.