This immense early Christian basilica, (543-554), combines antique and Byzantine influences. Its three naves are separated by two rows of arcades standing on marble columns imported from Constantinople, with finely carved capitals. However, the most exceptional feature is in the apse and on the triumphal arch: mosaics depicting hieratic characters on a gold background. Go across the superb atrium and up the bell tower for a fantastic view of the city and sea.