Contrasting sharply with the industrial scenery of the nearby port, the Chiesa di Santa Maria della Piazza is one of Ancona's showpiece churches. Its distinct Romanesque form, which comprises a fine marble facade and elaborate arched portal, dates from the 13th century when it was built over an earlier paleo-Christian basilica. Remains of this early basilica can still be seen beneath the main church – particularly striking are the mosaic floors and traces of 4th- to 6th-century frescoes.