The outer façade was commissioned by Pope Pius IV to Michelangelo, who in turn assigned the task to Nanni di Baccio Bigio: he erected the gate between 1562 and 1565, taking inspiration from the Arch of Titus.

The four columns of the façade come from the former St. Peter's Basilica and they frame the single, great archway, overlooked by the stone commemorating the restoration and by the papal coat of arms sustained by two cornucopias; the former circular towers were replaced with two powerful square watchtowers and the whole building was garnished with elegant battlements.

The positioning of the inscription - on the inner façade instead of the outer one, where it would have been visible while accessing the town - and the quite short text itself, are nonetheless singular; Cesare D'Onofrio deduces that probably the Pope would hold off the intrusiveness and the lively personality of the newly converted former queen, together with all the relevant diplomatic involvements.

The visit was nonetheless a memorable event for Roman people, both for the profusion of pomp and splendor and for the annoyance of merchants and peddlers, which were forced to suspend for some days their activities, in order to allow the cleaning and to maintain the decency all along the itinerary of the cortège from Porta del Popolo to St. Peter's Basilica.

[1] Other spectacular cortèges had already passed through the gate: the most impressive was the one of the French army of Charles VIII, which on December 31, 1494, paraded for six hours, giving am uncommon demonstration of military power; but also che processions of the cardinals, gathering into consistory with the Pope in the lead, aroused the enthusiastic and respectful admiration of the people.