Ключевые слова: ancient, archeology, brick, bulgaria, diokletian, europe, hisar, hisaria, hisarya, hissar, hissaria, hissarya, historical, landmark, mountain, outdoor, park, plovdiv, remains, resort, roman, ruins, sight, sights, sightseeing, spa, sredna gora, stone, structure, thrace, tourism, touristic, town, vacation, wall,