Piazza Maggiore and Basilica di San Petronio

Piazza Maggiore is the main square of Bologna and one of the finest medieval piazzas in Italy. On the north side is the Palazzo del Podesta and the Palazzo Re Enzo (where King Enzo of Sardinia was imprisoned for 23 years after the 1249 Battle of Fossalta). On the east side is the Palazzo Comunale. In the centre is the Fontana del Nettuno (Neptune Fountain, 1566, by Giambologna, the bronze Neptune with bronze mermaids, moved to the adjacent piazza for restoration but returning). The Basilica di San Petronio occupies the entire south side. It was begun in 1390 and intended to be the largest church in the world: larger than St Peter's in Rome. The Pope got nervous and redirected the funding to Rome. The basilica was never completed (the facade is still partially brick at the top, the marble cladding runs out about halfway up). It is the fifth-largest church in the world by volume as it stands, free to enter, with a floor plan that would have been the largest in Christendom. Inside: the meridian line on the floor (the longest sundial in the world, 67 metres, built in 1655 by astronomer Giovanni Cassini, used to determine the exact date of Easter) and the Chapel of the Magi with a fresco by Giovanni da Modena depicting Mohammed in Hell (controversial, has been a target of terrorist threats).