[a] It was later named Porta Turrionis, as it rose alongside the tower (whose building date is uncertain, but surely restored by Antonio da Sangallo the Younger during the papacy of Paul III), that is still visible at the entrance of Galleria Principe Amedeo.

When Pope Pius IV built the barracks of the Cavalry Guard Regiment in the vicinity, the gate took the name it still bears.

On the other hand Stefano Piale, on the basis of a 1590 document and some previous quotes, maintains that it was built by Pope Nicholas V, thus dating it back to mid-14th century.

Other quotes even backdate it to the building of the walls of Pope Leo IV, in about 850, but they appear to be scarcely reliable, as they clash with most of the texts, some of which are absolutely accredited.

[1] On the top of the arch are still visible two coats of arms of the House of Borgia, placed by Pope Alexander VI in memory of the restoration works that involved the gate and the surrounding stretch of wall about in 1500.