Templo Mayor

The Mexica founded Tenochtitlan on a marshy island around 1325, and the first shrine on this spot went up soon after. As the city grew into the dominant power of central Mexico, so did its temple. Successive rulers enlarged it, each rebuilding encasing the last, so the pyramid you see is really seven temples stacked inside one another.

In 1487 the ruler Ahuitzotl reconsecrated a vastly expanded temple in a dedication that lasted several days. Human sacrifice was central to the rites here, understood by the Mexica as the debt that kept the sun moving and the rains coming. When Hernán Cortés and his allies took the city in 1521, they pulled the temple down and raised the Spanish capital over the rubble.

The exposed ruins are the lower platforms and stairways of those stacked pyramids, not the tall summit, which was destroyed. On the south side stood Huitzilopochtli's shrine, on the north side Tlaloc's, each reached by its own staircase. Fragments of the original stucco, serpent heads, and a rack for skulls still mark the ground.

Around and beneath the platforms, archaeologists have lifted more than 200 sealed offering caches. They hold jade, shells, coral, jaguar and eagle remains, obsidian, and objects carried in from far corners of Mesoamerica, buried as gifts to the two gods.

On 21 February 1978 electricity workers digging behind the cathedral struck a huge carved disk, about 3.25 metres across. It showed Coyolxauhqui, the moon goddess, beheaded and dismembered, her limbs splayed around the stone.

The image retells a founding myth. Coyolxauhqui led her brothers against their mother Coatlicue, and Huitzilopochtli sprang out fully armed to defend her, killing his sister and throwing her broken body down the mountain. The disk lay at the foot of Huitzilopochtli's stairway, so victims cast down the steps fell onto the same fate as the goddess. The find set off the Templo Mayor Project under Eduardo Matos Moctezuma, one of the great excavations of the twentieth century.

For the Mexica the temple was not one mountain but two. Huitzilopochtli's side stood for Coatepec, the Serpent Mountain where he was born in battle. Tlaloc's side stood for the Hill of Sustenance, the source of water and maize.

Together they made the temple the centre of the universe, the fixed point from which the four directions and the layers of sky and underworld unfolded. Ceremonies here were meant to hold that order in place. To stand at the base is to stand where the Mexica believed the world was anchored.

Raised metal walkways carry you over the layered platforms, close to the serpent heads and the altars. The path leads into the site museum, arranged in two halves that echo the twin dedication, with the Coyolxauhqui disk and the colossal Tlaltecuhtli monolith among its centrepieces.

The setting is startling: Aztec stone below, the baroque cathedral and the modern square all around, five centuries pressed into one block of the city.