Basilica di San Lorenzo

It's difficult not to be bowled over by this oft-ignored hotchpotch of towers, lodges, apses and domes. In spite of appearances, it really is the one basilica. At its centre is an early-Christian circular structure with three adjoining octagonal chapels, dating to the 4th century. What's left of a Romanesque atrium leads to the heart of the church and before it stand 16 Roman columns, now a hang-out for kissing teens.