The construction date of the Ali Aga Mosque is uncertain, but it is believed to have been built around 1700. The mosque, which is now in ruins, was probably rebuilt and given his name by Miralay (colonel) Ahmet Aga, the castle commander. One of the island's two neighborhoods, Alaybey Mahallesi, is named after the mosque. The mosque is constructed of red cut stone and features a double-winged wooden door with a low arch on the north facade, accessed by five stone steps. Its minaret is made of white cut stone and is located in the northwest corner.