Basilica di San Petronio

Dominating the piazza’s southern flank, the Gothic Basilica di San Petronio ([tel]051 22 54 42; [hours]7.45am-12.30pm & 3.30-6pm) is Bologna’s greatest church. Dedicated to the city’s pat­ron saint and measuring 132m by 66m by 47m, it’s the world’s fifth-largest basilica. Surprisingly, though, it was never finished. Originally it was intended to be larger than St Peter’s in Rome, but in 1561, some 169 years after building had started, Pope Pius IV blocked construction by commissioning a new university on the basilica’s eastern flank. As a result the facade was never completed and if you walk along Via dell’Archiginnasio you can see semiconstructed apses poking out oddly.

The central doorway, carved in 1425 by Jacopo della Quercia, boasts a beautiful Madonna and Child and scenes from the Old and New Testaments; inside, chapels contain frescoes by Giovanni da Modena and Jacopo di Paolo. Note also the huge sundial that stretches 67.7m along the floor of the eastern aisle. Designed in 1656 by Gian Cassini and Domenico Guglielmi, it was instrumental in discovering the anomalies of the Julian calendar and led to the creation of the leap year.