The Gymnasium was built in the reign of Hadrian, and is entered from the Harbour Road. It is an elliptical-planned, mosaic-paved open court, above which is the gate leading to the Atrium. A portal flanked on either side with bull-heads bearing gems, leads to two pools. The building, which measures 40×20 m. has a palaestra in the centre, as in other gymnasia of this sort, surrounded by cells used by the students for various purposes. The palaestra is faced with coloured marble plaques. An imperial hall, absidal in plan, flanks the northern wall. The Gymnasium was two-storeyed, and to the east is the Verulanus Stadium, built by the chief priest of Asia during the reign of Hadrian (117-138 AD.), the largest of a series of sports facilities lining the length of the Harbour Road. It measures 200×240 m. and stretches from the Theatre Gymnasium at one end to the Harbour Gymnasium at the other.
Access to the main road is via a five sectioned portal leading out to a narrow connecting alley. The Stadium consists of a track surrounded by a marble-paved triple columned portico, with access to the Gymnasium on its western flank.