Pirot Fortress

Momchilov grad (Momchilo's fortress) is situated in Pirot, Serbia. It was built in the 14th century by Bulgarian brigand and local ruler Momchil.^[2] In 1344, the regency concluded a further alliance with Bulgaria, which required the surrender of Philippopolis (Plovdiv) and nine other towns in northern Thrace along the river Evros. Nevertheless, after their occupation, Ivan Alexander refrained from direct action against John VI Kantakouzenos' forces operating in southern and eastern Thrace.^[3] At the same time, Momchil, a former brigand whom Kantakouzenos had entrusted with control over the Merope (region) in the Rhodope mountains, switched over to the regency.^[2] It was supposed to serve as a defense against the Turks on the busy road which led from Belgrade to Constantinople.

• http://en.wikipedia.org/wiki/Pirot Fortress