Below the castle is an Armenian church known as Surb Arak'elots, the Church of the Holy Apostles. Built in the 930s, it has a tetraconch plan (a square with four semicircular apses) surmounted by a spherical dome on a cylindrical drum. On the exterior, the drum of contains bas-relief depictions of twelve figures, usually interpreted as representing the Twelve Apostles. The dome has a conical roof. The church was converted to a mosque in 1579, and then converted into a Russian Orthodox church in the 1880s. The Russians built porches in front of the church's three entrances, and an elaborate clocktower (now demolished) next to the church. The church was used as a warehouse from the 1930s, and it housed a small museum from 1963 until the late 1970s. Then the building was left to itself for about two decades, until it was converted into a mosque in 1993. In the same district of Kars are two other ruined Armenian churches. A Russian church from the 1900s was converted to a mosque in the 1980s after serving as a school gymnasium.