Opened in the 16th century, this gate is a very late addition to the ancient Roman Aurelian Walls, a 19-kilometres-long defensive circle of walls, which was meant to protect the inner city of Rome.
The walls were built in the 3rd century AD, with the use of advanced construction materials like concrete. At some places, they reach the height of 10 meters.
Built at the orders of Pope Gregory XIII., the gate can be easily recognized by its decorative style, which stands in sharp contrast with the military nature of the original wall.
Wikipedia https://en.wikipedia.org/wiki/Porta_San_Giovanni_(Rome)
Address Piazza di Porta S. Giovanni, Rome, Italy
Coordinates 41°53'9.234" N 12°30'33.593" E