ARCHAEOLOGICAL EXCAVATIONS IN DIOCLETIANOPOLIS (Mitko Madzharov – m_madjarov@abv.bg, Dimitrinka Tancheva) Room No. 2 in the thermae was explored. The stratum was 80 cm thick and contained building material, fragments of bricks from the vault of the ceiling and Late Antique sherds. Two columns built of bricks, which supported the vault of the ceiling, were discovered in the middle of the room. The walls of the room were preserved up to 4.50 m in height. They were built in opus mixtum with bands of three courses of bricks. Three niches were documented in the eastern wall. Their thresholds were situated at 30 cm above the floor, which was paved with bricks arranged over a plaster of mortar. The jambs of the entrance between rooms Nos.1 and 2 were built of bricks. The entrance was 2.70 m high and ended with an arch built of bricks. Its threshold was built of ashlars and bricks. A water-conduit, 10 cm wide and 15 cm high, was discovered in room No. 2. It was directed towards the near mineral spring situated to the northwest from the thermae. This mineral spring provided water for the eastern part of the thermae. The water-conduit ended with a shaft built of bricks bonded with mortar, 87 cm by 65 cm in size and 47 cm in depth. The mineral water ran from the shaft into the northern pool of room No. 1 (caldarium) through a terracotta pipe. A second shaft connected with the water-conduit and built of bricks bonded with mortar, 43.5 cm by 43.5 cm in size and 53 cm deep, was discovered at 6.04 m to the northwest of the first one. Both shafts were covered with bricks bonded with mortar. The shafts served as mud boxes where the water was purified from the impurities.