Their route was delimited by the two branches of the Bacchiglione, the Tronco Maestro and the Naviglio Interno, which came to be used as defensive ditches.
The Porta Molino's upper stories were used at the end of the 19th century as a reservoir the town's first drinking water system, though tales of the tower being used as an observatory by Galileo Galilei during his time in the city are probably false.
The Porta Altinate fronted onto the Naviglio Interno, crossed by an ancient Roman three-arch bridge (the Naviglio and the bridge were buried in the 1960s), and in 1256 this gate was stormed and destroyed by crusaders fighting against Ezzelino da Romano (as recorded in an inscription recorded by Carlo Leoni).
Almost nothing remains of them, since they were demolished during the War of the League of Cambrai to create the Renaissance wall - some sections can be seen in via delle Dimesse, near the Prato della Valle.
The gates include: Recent discussions about the city walls have discussed creating a green ring around them, a green lung as envisioned by the town planner Luigi Piccinato, though recent works seem to be moving in the opposite direction (including the controversial monument "Memory and Light" by the architect Daniel Libeskind in the golena of the Porte Contarine).