This was the building located at the beginning of the Harbour Street near the Theatre. The excavation is not completed. It had a palaestra (sports ground) on the street. At the point where the palaestra joined the main building there were rows of seats for those who watched the exercises. The Gymnasium had a great number of rooms which were used as classrooms, dormitories and libraries.
The Emperor's Hall in which stood a bust of the emperor was at the northern end. The building faced more towards the Marble Street which continued after the Theatre. From the gymnasium onwards about a 150-metre long section of the street was excavated and part of the columns on either side were erected. A part of this section of the Sacred Road was repaired after the earthquakes of the 4th century and the rest was left as it was. In this section traces left by Roman chariots on the marble paving, reaching in places 10 centimetres in depth, were preserved.
The large marble cauldron (omphalos) left at the side of the street in a partly broken state belonged to the unexcavated building nearby. This building, a wall of which was in the form of an apse, is said to be a synagogue. From here a street led west. This not yet excavated street ran along the Church of the Virgin Mary (the Council Church) to reach unknown buildings below.