Bolo Haouz Mosque is a historical mosque in Bukhara, Uzbekistan. Built in 1712, on the opposite side of the citadel of Ark in Registan district, it is inscribed in the UNESCO World Heritage Site list along with other parts of the historic city. It served as a Friday mosque during the time when the emir of Bukhara was being subjugated under the Bolshevik Russian rule in the 1920s. Thin columns made of painted wood were added to the frontal part of the iwan (entrance) in 1917, additionally supporting the bulged roof of summer prayer room. The columns are decorated with colored muqarnas.