Buried 5m underground, this mosque was spared from Mongolian and Timurid destruction before being rediscovered by Russian archaeologists. A far cry from the decorative splendour and turquoise domes of other buildings, it is worth a visit for its brick arrangements as well as the geometrical patterns carved on its façades and enhanced with majolica or, formerly, with alabaster. The south portal dates from the 12C. Inside you can still see the remains of the Zoroastrian temple and Buddhist monastery that stood here before the mosque.