HISARLAKA FORTRESS (Doichin Grozdanov – doichyn_eg@abv.bg) Explorations were carried out in the Late Antique and Mediaeval fortress. Five dolia were discovered close to the staircase at the triangular towers on the southern fortification wall. A stratum, 40 – 50 cm thick, containing sherds of the 10th – 12th centuries, fragments from tegulae and bricks, an axe, a small knife, horseshoes and animal bones was discovered to the north of the gate close to Tower No. 4 on the eastern fortification wall. Part of a room built in opus mixtum and situated close to the fortification wall was discovered in the lower stratum. A base of a column, a dolium and a fragment of terracotta lamp of the 4th century AD were found. The southern threshold stone and the foundations of the pilasters that supported the arch of the eastern fortification gate were discovered. The gate was 3.10 m wide and was explored in 1978. A drain was discovered beneath the street that started from the gate. A room with a floor paved with bricks and pilasters, belonging to an earlier building, was discovered beneath the fortification wall. Three walls of buildings were partly discovered at the inner side of the fortification wall close to the eastern gate. One of the buildings probably was barracks. Part of a room of a building was discovered close to Towers Nos. 2 and 3 at the eastern fortification wall and two dolia were found close to it. The fortification wall close to Tower No. 3 cut a wall of an earlier building.