Porta Pia was one of the northern gates in the Aurelian Walls of Rome, Italy. One of Pope Pius IV’s civic improvements to the city, it is named after him. Situated at the end of a new street, the Via Pia, it was designed by Michelangelo to replace the Porta Nomentana situated several hundred meters southwards, which was closed up at the same time. Construction began in 1561 and ended in 1565, after the artist’s death. A 1561 bronze commemorative medal by Gian Federico Bonzagna [it] shows an early plan by Michelangelo, very different from his final design. The façade on the outside of the city was completed in 1869 under the Neo-Classicist design by Virginio Vespignani.
A replacement was needed because of the new urban area, which could no longer provide access through the ancient Porta Nomentana for the Via Nomentana. According to Vasari, Michelangelo presented three different designs to the Pope, which were beautiful but too extravagant, and the Pope (perhaps not very convinced by certain details of the drawings) chose the cheapest of the three. No trace survives of the three drawings (except for some sketches for certain details), nor is it certain that the work was actually carried out to the original plan. The present appearance underwent several changes: the designs depicted on a commemorative coin minted in 1561 and in an engraving of 1568 (the only documentation of this epoch) present the Porta Pia quite differently from how it appears today. Moreover, even forty years after its construction, the gate was shown on maps of Rome as almost like a ruin. In any case, the gate depicted on the coin appears to be the closest to the initial plan, although we cannot exclude the possibility that in the course of works some variations and reviews were made to the design and its details, remembering that the Pope chose the cheapest design. It was, however, Michelangelo’s last architectural work – he died shortly before the work was completed. The work was carried out by Giacomo Del Duca, who also built Porta San Giovanni.