The Basilica was a magnificent building which functioned as a reception and audience hall. It had a rectangular plan with a semi-circular apse on its south side, and a vestibule with a mosaic floor on its north. The building measured 24 x 67 meters on its exterior, rose to a height of around 30 meters, and was roofed. Its longitudinal axis lay parallel to the west side of the Hippodrome. Between the two structures was a road nine meters in width. The Basilica faced the “Apsidal Hall”, with which it shared a common courtyard with surrounding portico. The Basilica had a single interior nave and its walls boasted marble revetments.
The construction of this building was completed in stages, and it was subjected to many alterations, chiefly in the floor structure and apse niches. Today, only the west wall masonry and the greater part of the apse of this monumental building are visible; the rest lies buried beneath the pedestrian walkway of Navarinou Square and D. Gounari Street.