The city of Tenochtitlan, de facto capital city of the Empire and one of the world's largest cities over the course of its history, was a finely planned metropolis built over Mexicoh Island, on the once great lake Texcoco, the place of today's Mexico City. The Mexica or the Aztecs, as they are popularly known, are an agglomeration of ethnic groups that formed the largest empire in Mesoamerica, known as Ēxcān Tlahtōlōyān, or Triple Alliance, at its core consisting of the allied city-states of Texcoco, Tlacopan, and Mexico-Tenochtitlan, and centered on the latter.
