ARCHAEOLOGICAL EXPLORATIONS IN DIOCLETIANOPOLIS (Mitko Madzharov – m_madjarov@abv.bg, Dimitrinka Tancheva) Southern room No. 1 of the thermae was explored. The floor was paved with small ashlars and had marble floor moldings and the walls were paneled with marble veneer. There are four niches on the northern and the southern side. The floor of the northern niche was paved with bricks, paneled with marble slabs. A pool, 7.70 m by 4.50 m in size and 1.20 m deep, was discovered. There were two steps and a handrail of bricks at the western side of the pool. The walls and the floor of the pool were paneled with marble slabs. The level of the spillway is equal to the level of the inlet of the pipe for filling the pool with mineral water. It shows that the pool was filled with water up to 1 m in depth. Two smaller pools, equal in size, were situated at the northern and southern side of room No. 1. Both pools were situated in vaulted niches and were built of bricks paneled with marble slabs. Each pool had a step and a handrail of bricks. The water-conduit came from the mineral spring located in the northern part of the complex and crossed adjacent room No. 2. The entrance between rooms Nos. 1 and 2 was discovered. Fragmentary Late Antique pottery and a marble votive relief of the Three Nymphs were found. Room No. 1 was a caldarium with three basins. The thermae were built at the end of the 3rd century AD, when Emperor Diocletian founded Diocletianopolis.