The church was built several times from its first nucleus in the fourth century. It was enlarged by instruction of Pope Leo III around the ninth century and again rebuilt in the twelfth. The current structure is from the work during the sixteenth and eighteenth centuries. The building plan is a Latin cross and the bell tower has three floors of Romanesque mullioned windows. The fine marble columns come from Minturnae. Artistic relief of the Chapel of the Sacrament of 1587 is covered with coloured marble, the candelabrum of the Easter candle 1264 and the pulpit is cosmatesque.