This is one of the great surviving triumphal arches from Imperial Rome. The place where these types of constructions originated, which over the centuries reached practically any place on the planet, although perhaps the most famous of them all is the Arc de Triomphe de la Estrella in Paris.
Arc of Constantine
But many centuries before the first ones were built in Rome, and they are arches that were not a door, nor were they attached to a wall or similar construction. It was independent constructions that were built with the aim of commemorating a military victory and the general or ruler who led it.
In this case, the Arch of Constantine, was obviously built in honor of Emperor Constantine I the Great, and the reason was to honor him for the victory in the Battle of the Milvian Bridge which took place in the year 312.
A few years later, specifically in 315, this arch was already built, located near the Colosseum and on the road that linked that place with the Palatine Hill. In fact, the arch is located in what was the Via Triumphalis through which the victorious generals of the battles passed and where the other two constructions of this type that have reached up to our days: the Arch of Titus and the Arch of Septimius Severus. Of the three, Constantine's is the most modern.
It has considerable dimensions as it reaches 21 meters high, with a base of 25 x 7 meters. It is not a single arch, but there are three, the central one being practically twice as tall and wide as the side ones.
The entire base of the monument was made with marble blocks, while the highest part is made of brick, to which marble finials were incorporated. And it is believed that much of this arch reused materials from previous monuments.
As a curiosity to say that on one of the two sides of the arch, the one facing the Palatine, there is a small door that communicates with an internal staircase formed in the thickness of the arch.
We have already said that this type of construction had a commemorative value, which is why there were many explanatory inscriptions that would originally be marked with bronze letters. The metal coating has not survived to this day, but the laudatory legend dedicated to Emperor Constantine can still be read here. And these inscriptions are endorsed by abundant reliefs of a laudatory nature.