St Petersburg is known for its impressive cathedrals. Visit three of them on a guided private tour. Easily recognizable by its massive gilded dome, St Isaac's Cathedral is both the city's largest Russian Orthodox cathedral and now also a museum. Marvel at its remarkable mosaics and climb to the dome's observation walkway for spectacular city views. Explore the Church of our Savior on Spilled Blood and learn how this onion-domed cathedral got its unique name, and see the active Kazan Cathedral—inspired by St. Peter's Basilica in Rome.