In the 4th century AD, the area of San Vittore al Corpo was occupied by a group of Paleo-Christian burial places and by the Imperial Mausoleum, known up until the 16th century as Saint Gregory's Rotunda. Remains of the foundations of the ancient octagonal building with semi-circular niches are visible beneath the facade of the basilica. The original core of the present-day church dates back to the 8th century, when an existing building was enlarged to house the relics of saints Victor and Satyr. In 1508 the Olivetan monks began remodelling the entire Benedictine complex, which had been founded shortly after the year 1000 by archibishop Arnolfo II.
The design of the church is the outcome of a long debate between the fathers who commissioned its construction and the leading architects of the day, including Vincenzo Seregni and Galeazzo Alessi. When the basilica was recuilt (work began in 1560) it faced in the opposite direction to its medieval predecessor. It has a main barrel-vaulted nave with side aisles divided off by pillars, a high dome and apsed presdytery. The incomplete facade has a lower row of Corinthian pilaster strips which were to have aligned with the portico that was never built, and a large semi-circulate window above.
The former Monastery of San Vittore, which now houses the National Museum of Science and Technology, is organised around two large square cloisters built between 1553 and 1587 with design contributions of Seregni and Alessi.
Remains of the fortified Imperial Mausoleum are visible in the cloisters. The monastery was suppressed in 1804 and used until 1940 as a military hospital, then as a barracks. Heavily damaged by bombing in World War II, it was restored by Piero Portaluppi and Ferdinando Reggiori (1949-53), who redesigned the surviving parts as museum spaces.