Porta Settimiana

Porta Settimiana was one of the three gateways in the Aurelian walls on the eastern side of the Tiber river. In the Middle Ages, the Via Recta left through this gate leading to the Tiber river port in Trastevere. It was restored at the dawn of the 15th century and then again in 1498 when Pope Alexander VI wanted to enhance it's military appeal. After marching out of the Vatican, Cesare Borgia left Rome through this gateway on his way to attack Romagna and the Villa Auditore.

Source

 * Assassin's Creed: Brotherhood