The Palacio Nacional, located on the eastern side of the Zócalo, is one of the oldest and most significant buildings in Mexico City. Built on the site of Moctezuma’s Palace, it was briefly the home of Hernán Cortés and, from 1562, became the seat of the viceroys of New Spain. For nearly three centuries, it was the administrative center of a vast viceregal territory. Its long facade of quarry and volcanic stone, spanning more than 200 m, responds to the sober language of viceregal civil architecture; the president enters through the Puerta Mariana for the Grito de Independencia. After independence, the building continued as the heart of political power and witnessed the Reform, the Porfiriato, the Revolution, and post-revolutionary governments. Today, in addition to serving as the seat of the Federal Executive Branch, much of the building functions as a museum, where visitors can encounter historical documents, courtyards, furnishings, and murals. Walking through it means entering centuries of national history and one of the clearest symbols of Mexico’s power and transformation.