The whole of the east side of the main square (Zocalo) is occupied by the National Palace(Palacio Nacional). Built of ubiquitous blood-red volcanic tenzontle stones and quarry stones, that the Spaniards recycled from the rubble of the Aztec temples they razed, it is the official residence of the President and houses various government offices. Originally built by the conquistador Cortes on the site of the Aztec ruler Moctezuma II's "New Palace", it was the seat of the Spanish viceroy's during the colonial period.

Above the large central doorway, surmounted by the Mexican coat-of-arms, hangs the Freedom Bell, rung by Miguel Hidalgo at Dolores on September 15, 1810 at the start of the War of Independence. Every year on September 15, the bell is rung by the President at 11pm and the "Grito de Dolores" is repeated from the balcony.

from: CODEX MENDOZA (Oxford; Bodleian Library)