Asen's Fortress (Bulgarian: Асенова крепост, Asenova krepost), identified by some researchers as Petrich (Петрич), is a medieval fortress in the Bulgarian Rhodope Mountains, 2 to 3 kilometres (1.2 to 1.9 mi) south of the town of Asenovgrad, on a high rocky ridge on the left bank of the Asenitsa River. Asen's Fortress is 279 metres (915 ft) above sea level.