The Kul Sharif Mosque located in Kazan Kremlin, was reputed to be – at the time of its construction – one of the largest mosques in Russia, and in Europe outside of Istanbul.
Wikipedia https://en.wikipedia.org/wiki/Kul_Sharif_Mosque
Official Website http://www.kul-sharif.com/
Phone +7 843 5678077
Coordinates 55°47'54.055" N 49°6'18.575" E
