On each side of the above-mentioned three chambers is a similar range of halls. The south-eastern wing (g), being the most perfect, serves as the better guide to the arrangement of this part of the building. We pass through two chambers (h) (i) containing fine mosaic pavement, and then reach a large long hall (g), which apparently consisted of three aisles and two semicircular tribunes, divided from each other by rows of columns, somewhat in the manner of a basilica. A considerable portion of the mosaics on the floor of this hall have been laid bare and may be seen amongst the ruins of the roof and upper part. In the larger tribune was discovered the great mosaic pavement of the Athletes, now preserved in the Lateran Museum, whence it has been inferred that this side hall as well as the corresponding one on the north-west side were used as gymnasia or ball courts (sphæristeria), with galleries for spectators. The purpose of the rooms situated on each side of the rotunda is not known, but it has been conjectured that they were additional tepidaria, since even the magnificent central tepidarium is hardly large enough to furnish the accommodation spoken of by Olympiodorus, who stated that there were 1600 marble seats for bathers in the Antonine Baths.[117] There were numerous chambers in the upper stories in and about these large halls, to which the staircases led, one of which has been restored. These were perhaps used as libraries, picture galleries, and museums of curiosities. The whole north-eastern side of the court which surrounded these central halls consists of ranges of rooms built of brick and opening outwards. Many of these are still standing, and the traces of an upper story are to be seen over some of them (j, j). Different opinions have been held as to their use. Some writers think that they were offices and rooms for the slaves belonging to the establishment, others that they were separate baths for women. The principal entrance to the enclosure was in the centre of this side of the court. On the north-western side of the court the remains can be traced of a large shallow tribune in the shape of a segment of a circle and surrounded by a vaulted corridor or cloister (k). Within this were three large apartments, probably used as lecture and conversation rooms. The rest of this side has entirely disappeared, as has also the opposite south-eastern side with the exception of one of the large apartments. These two sides of the court probably correspond in the same way as the wings of the central building. The fourth side of the court was occupied by an immense reservoir of water divided into numerous compartments (l), in front of which was the cavea of a stadium (m), and on each side two large halls, possibly used as dressing-rooms and gymnasia (n, n). The reservoir was supplied with water by a branch aqueduct from the Aqua Marcia.