Kosti (Bulgarian: Кости, stressed on the last syllable, formerly Greek: Κωστί - Kosti) is a village in southeastern Bulgaria, part of Tsarevo Municipality, Burgas Province. It is located on the banks of the Veleka River in the Strandzha mountains not far from the Turkish border, 20-25 kilometres south of Tsarevo and 91 km southeast of Burgas. As of June 2008, it has a population of 320[1] and the mayor is Iliya Yazov. The village lies within Strandzha Nature Park.
Traces of ancient metallurgical activity have been discovered in the vicinity of Kosti, as well as a big necropolis and several independent mounds of Thracian origin. The modern village was first mentioned in an Ottoman tax register of 1498, according to which Kosti's population consisted of 22 Christian families. It also featured in a 17th-century tax register, and during the Russo-Turkish War of 1828-1829 it was described as a Greek village (see Greeks in Bulgaria). Statistics of 1898 count 185 Greek and 25 Bulgarian houses, whereas 1897 data only notes 300 Greek houses.
Kosti was one of the Greek villages of inland Strandzha, culturally and linguistically very distant from then-Greek-inhabited nearby coastal towns like Tsarevo (Vassiliko) and Ahtopol. The local houses differ significantly from the typical village houses of Strandzha and the town houses of the coast. The houses in Kosti typically have two stories of crude stone, with the top floor cased with thick oak boards. They feature an unusually large fireplace on the top floor and the reported lack of any windows (which were later added by the Bulgarians who settled), as the only light to enter the room would come from a small opening in the ceiling called okno. The population was mainly engaged in agriculture, cattle breeding and logging (wood was in demand by the Ahtopol shipyard).