Tenochtitlan was the capital of the Aztec polity, a city built on land reclaimed from the shallow waters of Lake Texcoco. According to legendary histories, the site was revealed to the Mexica by an omen, an eagle seated on a cactus. The sacred nature of the city was marked by the construction of a walled enclosure with shrines, a ballcourt, skull-rack, and as its most elaborated building, the Great Temple with its double shrines to Huitzilopochtli and Tlaloc. The secular part of the city was divided into four quarters, and when the Spanish first entered the city in 1519, probably housed about 200,000 people in an area of about 6.5 square miles. The city was united by a network of roads and canals, and causeways and aqueducts extended to the neighboring shoreline. In each quarter of the city there were public spaces marked by a temple and plaza where city administrators carried out their duties as judges and representatives of the city government. In turn, each quadrant was divided into neighborhoods sharing a common school and local temple, and provided with a local military officer.