Ani's 1072 Manuçehr Camii was built by the Seljuk Turks, using Armenian architects and artisans, creating a stylistic blend in what is considered to have been the first Turkish mosque in Anatolia. With a tall octagonal minaret and six surviving vaults, it's relatively well preserved. The refreshingly cool interior features red-and-black stonework with polychrome stone inlays adorning the ceilings.
It provides superb framed views through stone window arches to the river and Silk Road 'bridge' ruin below, but beware of the gaping rectangular hole to the left as you enter: there's no health and safety allowances here.