The Arch of Galerius was built in 305 AD, to celebrate the definitive triumph of the Emperor over the Persians..

The whole structure consisted of 4 main pillars and 2 smaller ones on each side, the former supporting a central dome. Through the latter, a connection to the Galerius Palace (to the south) and to the Rotunda (to the north) was possible. Today, only a part of the monument still stands and there is no information on the period or the circumstances under which the rest of the arch was destroyed.

The Arch of Galerius belongs to the Galerius group of buildings, in the SE part of the historical center of Thessaloniki. From the original triumphal arch only three pillars and a part of the brick masonry above are preserved to the present day. The two main pillars are covered with sculpted marble slabs, which narrate the wars of Galerius against the Persians. The central arched opening is 9.7 m wide and 12.5 m high and the secondary 4.85 m and 6.5 m respectively.