The palace of Galerius Maximus in Navarinou Square was the administrative and religious centre of Roman Thessaloniki. The extant central core of the ruins is formed of four corridors enclosing a complex of buildings around a central court. This complex also included the Hippodrome, the Octagon, the Arch of Galerius and probably the Rotunda, and was an imposing symbol of Roman sovereignty in Thessaloniki. Within the palace complex excavations have unearthed mosaic floors. The most important building in the complex was the Octagon, an eight-sided structure in the southwest corner of the palace that was used as a throne room. Built in about AD 300, it is 30 metres in diameter and its marble floor is a work of art of exceptionally fine quality.