Russian Orthodox Church, Baden-Baden

This church was built 1881-82 by St. Petersburg architect Ivan Strom (or Schtrom), who also worked on St. Vladimir's Cathedral in Kiev.

The Salviati mosaic of The Transfiguration above the entrance was ordered by Baroness Plessen, a close relative of Tsar Nicholas II, and may have been designed by Russian painter Grigor Gagarin.

Sources:
Wikimedia Commons
Wikipedia DE
Barr, Sheldon. Venetian Glass Mosaics: 1860-1917. London: Antique Collectors' Club, 2008. 130.