St Sampson's Cathedral (Rus. Сампсониевский собор) is the oldest surviving church in St. Petersburg. It stands on the northern outskirts of the city and gives its name to Sampsonievsky Avenue. Rumor has it that it was in St. Sampson's Church that Catherine II of Russia secretly married Grigory Potemkin in 1774. Wikimedia Commons has media related to Sampsonievsky Cathedral.