Built in 1596–1598 to mark the passage of Margaret of Austria-Stiria en route to marry Philip III of Spain, this triumphal arch replaced a plainer medieval gate in the Spanish Walls that once ringed the city. Three arched passages in the Doric order, with Baroque sculptural friezes, give it a grander treatment than the other gates on the same fortification circuit — attributed to Aurelio Trezzi.
The walls themselves are long gone, and the arch now stands isolated on a traffic island in Piazza Medaglie d'Oro at the foot of Corso di Porta Romana, disconnected from the bastions it once anchored, fragments of which survive nearby. It marks the start of Corso di Porta Romana and the walk south toward Fondazione Prada.