One of the most photographed buildings in the Western Hemisphere stares back at you in full Vistacolor glory — Juan O'Gorman's extraordinary stone mosaic wrapping the Central Library of Mexico's National Autonomous University (UNAM), its four exterior walls clad in millions of hand-placed natural colored stones depicting pre-Hispanic and colonial Mexican history. Photographer Mark Turok captured the south and east facades in this chrome-era card, revealing the atomic-age symbol alongside Aztec calendars, colonial coats of arms, and the eagle-and-serpent — a collision of civilizations frozen in tesserae. The library tower, completed in 1956 and now a UNESCO World Heritage Site, was commissioned as part of the grand University City campus designed by a team including Mario Pani and Enrique del Moral. O'Gorman, a friend of Diego and Frida, had already revolutionized Mexican functionalist architecture before turning to mosaic as his true medium. The "25" penciled in the stamp box suggests this was priced at 25 centavos at retail — a bargain for a card that distills an entire civilization's self-image into 3.5 × 5.5 inches.