The Tuo Koto Nan Ampek Mosque (Indonesian: Masjid Tuo Koto Nan Ampek), also known as Gadang Balai Nan Duo Mosque is one of the oldest mosques in Indonesia located in Koto Nan Ampek Nagari, now administratively included into the area of Balai Nan Duo village, West Payakumbuh District, city of Payakumbuh, West Sumatera. The Minangkabau architecture is thought to have been built in 1840, which was originally covered with fiber roofs before being replaced with zinc. Currently other than being used for Muslim worship activities, this single-level mosque is also used by the surrounding community as a means of religious education.