the best preserved and most notable feature of asen's fortress is the church of the holy mother of god from the 12th-13th century. it is a two-storey cross-domed single-naved building with a wide narthex and a large rectangular tower, and features mural paintings from the 14th century. the conservation and partial restoration works on the church were finished in 1991 (the whole fortress was left to decay after the ottoman conquest in the 14th century and only the church remained standing in its original appearance as it was used by the local christians) and now it is in regular use as a bulgarian orthodox church.