The heart of Mexico City is the Plaza de la Constitución. Residents began calling it the Zócalo, meaning ‘base,’ in the 19th century, when plans for a major monument to independence went unrealized, leaving only the pedestal. Measuring 220m from north to south, and 240m from east to west, it’s one of the world’s largest city squares.

The ceremonial center of Aztec Tenochtitlán, known as the Teocalli, lay immediately northeast of the Zócalo. In the 1520s Cortés paved the plaza with stones from the ruins of the complex. In the 18th century the Zócalo was given over to a maze of market stalls until it was dismantled by General Santa Anna, who placed the unfinished monument in its center.

Today the Zócalo is home to the powers that be. On its east side is the Palacio Nacional (the presidential palace), on the north is the Catedral Metropolitana, and on the south are the city government offices. Jewelry shops and extravagant hotels line the arcade known as the Portal de Mercaderes on the plaza’s west side.

As you emerge from metro Zócalo onto the vast central plaza, you may hear the booming of drums from the direction of the cathedral – the Aztec dancers are doing their thing. Wearing snakeskin loincloths, elaborately feathered headdresses and shell ankle bracelets, they move in a circle and chant in Náhuatl. At the center, engulfed in a cloud of fragrant copal smoke, drummers bang on the conga-like huehuetl (indigenous drum) and the barrel-shaped, slitted teponaztli.

Variously known as Danzantes Aztecas, Danza Chichimeca or Concheros, the dancers perform their ritual daily in the plaza. It is meant to evoke the Aztec mitote, a frenzied ceremony performed by preconquest Mexicans at harvest times, although scant evidence exists that the dancers’ moves bear any resemblance to those of their forebears.

The square has variously served as a forum for mass protests, free concerts, a human chessboard, a gallery of spooky Día de Muertos (Day of the Dead) altars and an ice-skating rink. It’s even been a canvas for photo artist Spencer Tunick, who filled the square with 18,000 nude Mexicans in May 2007.

The huge Mexican flag flying in the middle of the Zócalo is ceremonially raised at 8am by soldiers of the Mexican army, then lowered at 6pm.