Mediolanum, the modern Milan, appears to have been founded by the Celts of Northern Italy around 600 BC and was conquered by the Romans around 222 BC, who gave it its Latin name. In the 4th century AD, at the time of the bishop St. Ambrose and emperor Theodosius I, the city became for a short time the capital of the Western Roman Empire.

Monuments

Some few monuments of the Roman period can still be seen:

• in the church of S. Ambrogio:
  • the Chapel of S. Vittore, with Late Antique mosaics
  • the so‑called "Tomb of Stilicho", assembled from a Roman sarcophagus and other material
  • a large collection of inscriptions
• the Colonne di San Lorenzo, a colonnade in front of the church of S. Lorenzo
• Roman lapidary material in the Archi di Porta Nuova
• the scant remains of an amphitheatre

The body of St. Ambrose (d. 397) and those possibly of SS. Gervasius and Protasius — or at any rate, of earlier men, found in St. Ambrose's time, are still to be seen in the crypt of the church of S. Ambrogio.