The arch of Trajan is a monument of rare beauty that leaves amazed not only for its majesty but also for its excellent state of preservation. The arch is one of the best preserved in Italy. Its construction began in 114 A.D. to celebrate the opening of Via Traiana, an alternative road to Via Appia, which served to connect Benevento to Brindisi more quickly.

The arch has only one fornix and consists of two main facades, one facing the city, where scenes of peace are depicted, and the other facing the outside, where military scenes are depicted. The interior sides of the fornix depict some scenes related to the activity of the emperor Trajan in Benevento. The arch is 15.60 meters high and 8.60 meters wide, in the center there is a dedicatory inscription against Caesar. The frame of the structure consists of limestone blocks with a coating of Parian marble.

Above the fornix there is a entablature with a frieze that immortalizes the procession of Trajan on Dacia. In ancient times the arch was surrounded by houses, but in 1850 the houses were demolished to allow the monument to rise in all its splendor.