Pre-Hispanic Xochimilco was an island connected to the mainland by three causeways. One of these still exists in the form of Avenida Guadalupe I.Ramirez, one of the city's main streets. This causeway led to the main ceremonial center of the town, which was called the Quilaztli. The Spanish destroyed the Quilaztli during the Conquest, and replaced it with the San Bernardino de Siena Church, which would become the social and political center of the colonial city. The city in turn, was the most important settlement in the south of the Valley of Mexico in the colonial era. It became a settlement of Spanish, criollos and mestizos, with the indigenous living in rural communities outside of the city proper.