The development of the two monumental gates is probably due to the extension of Via Amerina all the way to Perugia, which entered the city through Porta Marzia and out through the Etruscan Arch. The project definitely cemented the alliance between the city and Rome!

While Porta Marzia to the south, full of symbolic value, represented a more welcoming entrance to those arriving in the city from the Tiber, Assisi, Orvieto or Rome, the Etruscan Arch to the north, leading toward Gubbio, was the only access along the walls for military purposes. The gate, also known as the Arch of Augustus, Porta Vecchia, Porta Boreale and Porta Pulchra, is flanked by two sturdy trapezoid-shaped towers, tapering upwards and rising to a height of about 20m. The arch of the door, about 10 meters high, is formed by a double ring of wedges, with the inscription "AUGUSTA PERUSIA", placed there at the time of the restructuring of the municipality of Perugia by the future emperor in the years immediately following the Perugia war (bellum perusinum, 41-40 BC). Higher up, along the bottom bezel of the frieze, is a second inscription COLONIA VIBIA, recording the status granted to the colony by the Emperor of Perugian origin, Vibius Trebonianus Gallus (251-253 AD). On the sides of the arch two protruding blocks of granite have been inserted, today the shape has worn, but they originally may have been human heads representing protective deities at the entrances. The elegant Renaissance loggia dates back to the Renaissance period, built on top of the left bastion and now the headquarters of the Authority for Archives, Heritage and Landscape of Umbria.