Next time you find yourself strolling along Kamergersky Pereulok near Tverskaya Ulitsa, look for a plaque in memory of Sergei Prokofiev, mounted on a massive wooden door. A former tenement house at 5/6 Kamergersky Pereulok is now the Sergei Prokofiev Museum, where the Russian composer and conductor spent the six last years of his life (1947 to 1953), working on the “On Guard for Peace Oratorio,” “Seventh Symphony,” and the ballet “The Tale of the Stone Flower.”