The gate, comprising a single archway faced with travertine, is situated in the Aurelian Walls a short distance from the old Porta Asinaria, which it replaced as an entrance to the city during the second half of the 16th century.
In 1564, Pope Pius IV had a passageway opened next to one of the towers in this stretch of walls, probably to provide an alternative entrance as the ancient gate was too low by then with respect to the surrounding ground. Later, at the wishes of Gregory XIII (1572–1585), the route was reorganized both inside the walls, towards the basilica of San Giovanni, and outside, towards the Castelli Romani, and a new gate was built.
The gate was designed by Giacomo del Duca, an architect of Sicilian origin, a former pupil and collaborator of Michelangelo on the realization of Porta Pia. De Duca was assisted by the master builders Bartolino and Giulio di Castello and Giovan Maria de Rubeis. The gate consisted of an arch decorated by oblique- and flat-cut rusticated blocks, between two giant pillars made up of alternating rows of rustic and smooth blocks. Above is the attic storey, with small balustrades and garland decoration by the pillars. In the centre is a plaque with an inscription commemorating the opening of the new gate, realized in 1574 “for [the] public utility and embellishment of the city”. Above it is the shield of a coat of arms, but without the heraldic elements. On the keystone is a Moorish head in marble, adorned with a garland of flowers and with a necklace of pearls around the neck, probably a reference to the glorious victory over the Ottoman Empire in the Battle of Lepanto (1571).
The proximity of San Giovanni in Laterano, Rome’s cathedral, must have determined the asymmetrical plan of the gate: there is a wider angle on the church side compared to the other one, almost inviting and directing the flow of pilgrims and citizens towards the basilica.
2. View of Porta San Giovanni, 18th century, print.
3. View of Porta San Giovanni and the Roman walls, 19th century, print.
4. Porta San Giovanni, exterior elevation, 16th century.
5. Porta San Giovanni, exterior elevation, main archway, detail of the Moor’s head, 16th century.
6. Porta San Giovanni, interior elevation, 16th century.
7. Porta San Giovanni, exterior elevation, detail of the attic storey, 16th century.