Michelangelo's last architectural work, this crenellated structure was commissioned by Pope Pius IV to replace Porta Nomentana, one of the original gates in the Aurelian Walls, and was built between 1561 and 1564.
Bitter street fighting took place here in 1870 as Italian troops breached the adjacent walls on 20 September to wrest the city from the pope and claim it for the nascent kingdom of Italy.