The Templo Mayor (Main Temple) in Tenochtitlan, capital of the mighty Aztec empire, was located in the center of the city, where the most important ritual and ceremonial activities in Aztec life took place. Standing about ninety feet high, the majestic structure consisted of two stepped pyramids rising side by side on a huge platform. It dominated both the Sacred Precinct and the entire city. The twin pyramids symbolized two sacred mountains; the one on the left represented Tonacatepetl, the Hill of Sustenance, whose patron deity was Tlaloc, the ancient god of rain; the one on the right represented the Hill of Coatepec, birthplace of the Aztec war god Huitzilopochtli. The temple structures on top of each pyramid were dedicated to and housed the images of the two important deities. Access to these shrines was by means of broad staircases, flanked by balustrades. Pairs of large, expertly carved serpent heads were placed at their base, while closer to the top sculptures of figures holding standards displayed banners made of bright paper and feathers.
The seven major building phases of the Templo Mayor began with a simple structure, probably dedicated to Huitzilopochtli, built in 1325 when Tenochtitlan was founded. Subsequently the Templo Mayor grew enormously both in size and elaboration resulting in the impressive structure seen by the Spaniards in 1519. Reconstructions and enlargements of the temple were sometimes necessary because of flooding and the unstable lakebed on which it was built. Most often, however, successive powerful rulers enhanced the temple to celebrate their own coronations, to honor the gods, and to validate the power of the Aztec empire. The most spectacular expansion of the Templo Mayor took place in the year "1 Rabbit" (1454 A.D.) under the ruler Motecuhzoma I when impressive art works and architectural elements were added.