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Piazza Maggiore & Basilica di San Petronio
Architecture
The main square, closed to traffic and functioning as the city's living room. San Petronio was planned to be larger than St Peter's in Rome; the money ran out, and the facade is still half brick and half marble, which is oddly moving. Inside runs a 67-metre meridian line laid by Cassini in 1655, still accurate enough to mark local noon by a beam of sunlight from a hole in the roof.
Free to enter the basilica. Look for the acoustic dead spot in the neighbouring Palazzo del Podestà's vaulted passage — whispers carry diagonally across it.