One day
Start under the Admiralty spire and cross Palace Square to the Hermitage for the morning. Walk out past St Isaac's Cathedral and the Bronze Horseman to the Neva, then up Nevsky Prospekt through Tsentralny — the Kazan Cathedral, the Singer House — turning off along the Griboyedov Canal to the Church of the Savior on Spilled Blood. End the evening at the Mariinsky in Kolomna if you can get a seat.