Basilica di San Lorenzo Maggiore

San Lorenzo Maggiore is a late-antique basilica outside Milan's former Roman walls. Its domed central plan, four semicircular exedrae, early mosaic chapel and ancient colonnade preserve the scale of the imperial city.

Why it matters

The regional heritage catalogue ranks San Lorenzo among the most celebrated churches of Milan, and with reason. Built in the late fourth century along the road towards Pavia, beyond the city walls but near the amphitheatre, imperial palace and circus, it is a building whose scale the regional heritage catalogue sets beside the great late-antique imperial churches of Rome and Ravenna — still retaining its original centralised scheme: a square core wrapped by four two-storey exedrae, bound together under a dome. Successive collapses and rebuilds — the dome itself was re-raised more than once, and the present facade is Cesare Nava's 1894 reworking — have never erased that geometry. The ancient colonnade remains a defining element of the basilica's setting.

What to notice

The central space opens into four exedrae connected by transverse arches, with galleries above the lower level. The baroque high altar incorporates ancient marbles from Sant'Aquilino. That octagonal chapel preserves fourth-century mosaics of saints and Christ among the apostles; San Ippolito and San Sisto are two further octagonal chapels. The Corinthian columns of the former quadriporticus stand outside, 8.5 metres tall, with a brick arch over the central bay and an inscription of Lucius Verus dated 167.

Context and history

Scholars still debate which Roman buildings supplied the great reused blocks that underpin the whole structure — the catalogue records the hypothesis that they came from the nearby amphitheatre, sunk four and a half metres to bridge a marshy hollow. Whatever the answer, the building's ambition suggests imperial patronage between the mid-fourth and early fifth centuries, and the catalogue ties its origin to the Easter clash of 385 between bishop Ambrose and an imperial court that wanted a church of its own. The medieval city kept it in use — fires in the late eleventh century and the earthquake of 1117 forced repairs without breaking the plan — and the 1930s isolation campaign cleared the houses packed around it, creating the open forecourt with its bronze copy of the Lateran Constantine and, behind the apses, the leafy Parco delle Vetra. The name "San Lorenzo alle Colonne", used for centuries, preserves the memory of the portico that always defined the approach.