Tuida Castle is a Late Roman, Byzantine, and medieval Bulgarian fortress crowning the Hisarlaka Hill in Sliven, eastern Bulgaria. Originally constructed in the 4th century AD, the fortress was continuously occupied and fortified until the 13th century, serving as the seat of a bishop from its earliest period. The site has undergone substantial restoration, with fortress walls reconstructed to their original heights between 1.6 and 2.2 meters. The modern complex features an exhibition area showcasing medieval weaponry and period clothing, a 400-seat amphitheater for performances, and panoramic views toward the Blue Stones mountains and Sliven city below.
