The basilica of Santa Maria in Trastevere was probably the first official place of Christian worship in Rome: a valid reason to make the church a must-see destination for any religious or spiritual itinerary in the capital. According to legend, it was built by Pope Calixtus I in the 3rd century and was completed by St Julius I in 340. It was later rebuilt during the pontificate of Pope Innocent II and then further decorated, although without major changes. It is embellished with mosaics depicting the "Life of the Virgin" by Pietro Cavallini (1291), on the façade and in the apse, and by those dating back to 1140 depicting Pope Innocent II himself. Outside, the 12th-century bell tower stands out. The ceiling, designed by Domenichino (1617), is spectacular, with the image of "The Assumption" in the centre.