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 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.

This rule probably was effective also for the members of the Imperial family, whose private means were parked in a reserved area (called Mutatorium Caesaris) just a little farther at the beginning of the Appian Way.

On the right jamb of the gate there is also a carved figure portraying Archangel Michael killing a drake, alongside of a blackletter inscription written in Medieval Latin, that commemorates the battle fought on 29 September 1327 (the day of Saint Michael) by Roman Ghibelline militiamen of the Colonnas, led by Giacomo de’ Pontani (or Ponziano), against the Guelph army of Robert of Anjou, King of Naples, led by John II and Gaetano Orsini: In addition to such remains, that are interesting from an historic viewpoint, the whole monument is noteworthy also for the abundance of graffiti traces that, though not official at all, provide evidence of the daily life that occurred around the gate along the centuries.

On the left jamb, in front of Archangel Michael, there are several crosses and a christogram (JHS with a cross above the H), probably carved by pilgrims; there are also several Italian and foreign names (a man by the name of Giuseppe Albani wrote his name three times) and dates, that can be deciphered back to 1622; somebody also carved a kind of road direction to Porta San Giovanni or St. John Lateran, addressed to foreign wanderers and still visible just outside the gate, on the left: “DI QUA SI VA A S. GIO…” (Italian for "Hither you go to S. Jo..."), interrupted by something or someone; as well as other signs and writing hard to decipher, such as the engraving “LXXV (underlined three times) DE L”, on the tower on the right.

Since the 5th century, and at least until the 15th, the farming out or the sell of town gates and of the toll collection for their transit to private citizens is attested as a usual practice.

Alongside of the west tower there are remains of a walled-in postern, placed above the ground level, whose peculiarity is the absence of traces of wear on the jambs, just as if it was locked soon after it was built.

As regards the interior, the most relevant changes are recent and date back to 1942-1943, when the whole structure was occupied and used by Ettore Muti, then the Secretary of the Fascist Party.