Porta Appia

The Porta San Sebastiano is the largest and one of the best-preserved gates passing through the Aurelian Walls in Rome (Italy).

Originally known as the Porta Appia, the gate sat astride the Appian Way, the regina viarum (queen of the roads), which originated at the Porta Capena in the Servian Wall. During the Middle Ages probably it was also called Accia (or Dazza or Datia), a name whose etymology is quite uncertain, but arguably associated with the river Almone, called "acqua Accia", that flowed nearby. A document ca. AD 1434 calls it Porta Domine quo vadis. The present name is attested only since the second half of 15th century, due to the vicinity to the Basilica of San Sebastiano and its catacombs.

The original structure was constructed by Aurelian ca. AD 275 and included a double-arched opening surmounted by bow windows and two semi-cylindrical towers. The façade was faced with travertine. After a later restoration, the towers were enlarged, increased, and linked, through two parallel walls, to the preexisting Arch of Drusus.

In AD 401-402 Emperor Honorius reshaped the gate with a single fornix and a higher attic with two rows of six bow windows each; it was also provided with an uncovered chemin de ronde with merlons. The bases of the towers were incorporated within two square-plan platforms, faced with marble. A later modification yielded the gate's present form, in which a floor has been added to the whole structure, towers included. Due to the absence of the usual plate commemorating the works, some archaeologists doubt that the work has not been carried out by Honorius, who left panegyric epigraphs on any other restored part of the walls or the gates.

The latch was released by means of two wooden gates and a shutter that rolled, through still visible grooves, from the control room placed above, whose supporting travertine shelves are still existing. Some notches on the jambs could indicate that wooden beams were also employed to strengthen the latch.

...
Wikipedia