Ahmed Bey Mosque was built in the middle of the 15th century. According to legend, it was erected on the foundation of the medieval Bulgarian Holy Week Cathedral. In 1734 it was reconstructed and expanded. In 1904, a minaret crashed due to a powerful earthquake. Today, Ahmed Bey Mosque does not function as a religious building, being at the same time an exhibition hall of the Kyustendil Museum and a cultural monument of national importance.