Asen's Fortress (, Asenova krepost), identified by some researchers as Petrich (Петрич), is a medieval fortress in the Bulgarian Rhodope Mountains, 2–3 km south of the town of Asenovgrad, on a high rocky ridge on the left bank of the Asenitsa River. Taken by the Byzantines after Ivan Asen II's death, the fortress was once again in Bulgarian hands at the time of Ivan Alexander in 1344 only to be conquered and destroyed by the Ottomans during their rule of Bulgaria. The town of Asenovgrad takes its modern name from the fortress, formerly being named Stanimaka.