This piazza is a popular spot for afternoon coffees and evening cocktails at its outdoor cafés, but the showpiece of the square is the 12th-century church of Santa Maria in Trastevere. The 13th-century mosaics on the church's facade -- which add light and color to the piazza, especially at night when they are in spotlight -- are believed to represent the Wise and Foolish Virgins. Inside, the enormous golden mosaic in the apse is the city's finest, a shining burst of Byzantine color and light set off by giant columns. In August, processions honoring the Virgin Mary gather at the church as part of Trastevere's traditional feast, called Festa de Noantri (Our Own Feast).