The defensive wall of Maediolanum

The walls, made of brick, were placed on a massive base protruding, in large pebbles inward and in large fragments of stone to the outside  to form a water-filled ditch. The Republican walls was 3500 meters long with 6 gates: Jovia, Vercellina, Ticinese, Romana, Eastern and Comasina. 
The door was constituted by a dual arc flanked by two towers.It was the custom that every door was consecrated to a pagan deity.

IOVIA GATE: The Republican name of this gate is unknown; later called "Iovia" in honor of Diocletian who so liked to be called;

VERCELLINA GATE: So called because oriented Vercelli. It was dedicated to the goddess Venus, of which there was a statue above the gate.

TICINESE GATE: so called because oriented "Ticinum" today Pavia. It was dedicated to Mercury, the god of commerce.

ROMANA GATE: so called because oriented Rome. It was dedicated, according to some, to Mars, according to others to Apollo. On its arch there was this inscription: "Tell, traveler who are going to pass this gate:'Hail second Rome, imperial decorum of the Kingdom; very venerable and full of riches city. People fear you; powerfull people bend their neck to you. In the use of the army Thebes, in the wisdom Athens you win.'" It is sure that Caesar passes this cage when he was directed towards Gaul.

ARGENTEA CAGE: It was dedicated to the Sun and to Apollo. The name derives  from the town where it was directed towards "Argentiolum" today Gorgonzola

COMASINA CAGE (OR CUMANA): It was dedicated to the Moon