On the north side of the Zocalo, which over the centuries, has sunk noticeably into the spongy subsoil, is the Catedral Metropolitana(Cathedral of Mexico City). Its lopsidedness is evident when viewed from across the square, but an engineering project to stabilize the structure has been in progress. Construction on this oldest and largest cathedral, of basalt and gray sandstone, in Latin America began in 1573 and continued intermittently throughout the next three centuries. The result is a harmonious effect of Baroque and neoclassical touches.

Inside are four identical domes, five altars and 14 chapels, mostly in the CHURRIGUERESQUE style, an extremely decorative form of Spanish Baroque from the mid 17th century. Its great glory is the richly carved Altar de los Reyes(Altar of the Kings, 1718-39) behind the high altar, with a retablo by Jeronimo de Balbas, a sculptor of the Churrigueresque school from Seville. The retablo, which follows the form of the apse, has paintings by Juan Rodriguez, including the "La Adoracion de los Reyes"(Adoration of the Kings) and the "Asuncion de Maria"(Assumption of the Virgin Mary), to which the Cathedral is dedicated.