The basilica complex on the slope of Tepeyac Hill, in the north of the city, is the spiritual centre of Mexican Catholicism. The shrine commemorates the apparitions of the Virgin Mary to the Nahua farmer Juan Diego in 1531, ten years after the conquest of the Aztec capital. The dark-skinned image she left on his cloak — the tilma — is preserved behind glass in the modern basilica and is the focus of unceasing pilgrimage.
Two basilicas stand on the site. The 18th-century Old Basilica is now propped up at one corner where it tilts on subsiding ground. The New Basilica, built in 1976 by Pedro Ramírez Vázquez, is a vast circular auditorium with no internal pillars, holding 10,000 worshippers; a moving walkway behind the altar shuffles pilgrims past the image. Crowds are constant; the days around 12 December are overwhelming.