Officially known as Plaza de la Constitución, El Zócalo is the main public square and one of the most recognizable places in Mexico City. It contains a giant Mexican flag at its center and has been the centerpiece of public gatherings since the days of the Aztecs. The site also hosts annual, widely attended religious events during Holy Week and for Corpus Christi. Several historic buildings also border the square, including the city’s national cathedral, the National Palace and federal buildings.
You could spend a couple hours looking around the Zócalo, and some travelers suggest you start your visit at sunset. Mexican soldiers march out into the square at sunset to take down the flag, offering a great photo opportunity. Some travelers even recommend heading to the square more than once.