Buzovo Kale

Buzovo Kale, or Buzova Fortress, is an Early Byzantine fortress on the northern slopes of Sarnena Sredna Gora, two kilometres southeast of Buzovgrad. It controls the Tundzha River valley and protects the Kazanlak Plain from attacks from the south. Situated at an elevation of 566 metres, it encloses seventeen decares and has an irregular quadrilateral plan.
The walls are built of rubble stone bonded with white mortar and fragments of brick. Some survive to heights of 3–3.5 metres. The western side has a double wall, and defensive towers reinforce the southern wall. Walls of a watchtower can be identified at the fortress's highest point, while excavated building foundations occupy the eastern part. A tower also stood at the 566-metre elevation, with ruins surviving to 3.50 metres. There may also have been an underground passage to the Tundzha River for the water supply.
Archaeological finds in the area include coins from Constantine the Great's reign and fragments of Early Byzantine pottery. The middle wall is thought to have existed in the Early Byzantine period.
According to legend, during the Ottoman invasion the fortress was besieged, and its governor, Buz Voivode, successfully defended it for seven months until the Turkish commander Ali Pasha shifted the siege. The legend relates how a captured child informed Buz Voivode about a tunnel used to obtain food and water, and how hunger and thirst eventually broke the resistance. During the night Buz Voivode ordered the people to leave the fortress and withdraw into Sredna Gora.