Bolo Haouz Mosque sits directly opposite the Ark citadel, separated from it by an open plaza, and was the emir's official Friday mosque. Its most distinctive feature is the 20-column wooden iwan added in 1917: slender painted columns supporting a carved timber ceiling decorated in blue, white, and gold, all reflected (once) in the hauz pool that gave the mosque its name. The portico is a masterpiece of traditional Bukharan carpentry and looks like nothing else in the city.
The mosque is still an active place of worship, and non-Muslim visitors are generally welcome outside of prayer times. The interior is modest compared to the elaborate exterior — the focus here is entirely on the iwan and its extraordinary columns. It is often bypassed by visitors who spend all their time at the Ark, but the combination of the citadel wall, the open square, and this elegant wooden facade makes for one of Bukhara's best compositions.