What is now the Basilica of Santa Maria in Trastevere was probably the first Christian place of worship in Rome. According to tradition, it was built by Pope Calixtus I in the 3rd century and was completed by St Julius I in 340. Rebuilt during the pontificate of Pope Innocent II, it was later decorated and restored, including by Pope Clement XI and Pope Pius IX. Many parts of the church date back to the 12th century, such as the mosaics on the façade and apse, created by Pietro Cavallini and depicting the ‘Life of the Virgin’, and the bell tower, with its square base.
The portico was remodelled in 1702 by Carlo Fontana and today houses fragments of friezes and ornaments from the ancient basilica, as well as Christian epigraphs, and is surmounted by a balustrade decorated with statues of four popes. The interior has three naves divided by twenty-two ancient granite columns of various diameters, all with Ionic and Corinthian capitals, probably from the Baths of Caracalla.
The ceiling, richly decorated with friezes, was designed by Domenichino in 1617 with an image of ‘The Assumption’ in the centre. In 1860, the floor was almost completely reconstructed by architect Vespignani with floor mosaics typical of the 13th century. In the basin and the apse arch, in addition to the mosaics with the stories of the Virgin Cavallini, are those made around 1140, after the death of Pope Innocent II.