Basilica di San Petronio

The biggest church Bologna could afford

The basilica takes the entire south side of Piazza Maggiore. It runs 132 meters long and 66 meters wide, rises about 47 meters, and holds something like 28,000 people, which puts it among the largest church buildings in the world.

It is not the cathedral. Bologna’s cathedral is San Pietro, a short walk north on Via dell’Indipendenza. San Petronio was a city project, paid for and run by the commune rather than the church, and dedicated to Bologna’s patron saint. That distinction explains a lot about the building, including why the money kept running out.

Construction began on 7 June 1390 to a design by Antonio di Vincenzo. The nave and apse were not finished until 1663, 273 years later.

Why the facade stops halfway up

Stand in front of it and the break is impossible to miss. The lower third is finished marble in pink and white, cut into panels and framed with sculpture. Above that line, bare brick.

Work on the marble started in 1538 and stopped. The version most guides tell is that Pope Pius IV had the Archiginnasio built hard against the basilica’s flank in 1562 to kill Arduino degli Arriguzzi’s plan for a church larger than St Peter’s in Rome. Recent historical work argues that story is a myth, and that the real causes were the ordinary ones: funding dried up and the plans kept changing.

Both versions are worth knowing, because you will hear the papal one repeated in the square all day.

The Cassini meridian line

Inside, down the left aisle, a brass line runs 66.8 meters across the floor with a calendar scale beside it. Giovanni Domenico Cassini laid it in 1655, using a pinhole set high in the vault to throw a disc of sunlight onto the pavement. Where the disc lands tells you the date. At the time it was reported to be the longest astronomical instrument of its kind anywhere.

It needs sun. On a gray November morning you will see a brass strip and a lot of tourists walking over it. Around solar noon on a clear day you get the bright oval crossing the line, which is worth timing a visit around.

The chapels

The side chapels are the reason to slow down rather than walk the nave and leave. The Bolognini Chapel, also called the Chapel of the Magi, has a Gothic marble balustrade of 1400 by Antonio di Vincenzo and a wooden triptych carrying 27 carved figures by Jacopo di Paolo.

That chapel sits on the paid route rather than the free part of the church. Everything else in the nave you can walk around for nothing.

Hours, tickets and what to wear

As of September 2026 the basilica opens daily 10:00 to 18:00, last entry 17:50, and entry is free. The museum and bookshop close at 17:30. The Cappella dei Magi route costs €5 full, €3 reduced for ages 11 to 18, over 65s and guided groups, €2 for school groups, and nothing for under 10s, disabled visitors and clergy. Hours and prices change, so check basilicadisanpetronio.org before you go.

This is a working church and the dress code is enforced at the door. Shoulders and knees covered, no tank tops or short skirts, hats off inside, and no luggage or large bags.

The panoramic terrace is closed permanently. Restoration finished and the terrace did not reopen, so any article telling you to climb it is out of date. For a view over the rooftops, look at the Due Torri or the clock tower at Palazzo d’Accursio instead.

Tips

• Arrive at opening. By eleven the nave has tour groups in it, and the meridian line is easier to read when nobody is standing on it.
• Travel light. Large bags are turned away at the door and there is no cloakroom to fall back on.
• Save the outside for late afternoon. Low sun rakes across the marble and the brick, and the color split is at its most dramatic then.
• Combine it with the rest of the square. The Fontana del Nettuno is at the far corner, and the Quadrilatero food streets start immediately behind Palazzo dei Banchi on the east side.
• If it is raining, Biblioteca Salaborsa is a two-minute walk and free.