Peter and Paul Castle is the main fortress of Saint Petersburg in Russia. It was founded by Peter the Great in 1703 according to Domenico Trezzini's designs as a city fortress. In the early 1920s, the Bolshevik government used it as a prison and execution place. Featuring a cathedral, a former prison, and various galleries, this large defensive fortress is the nucleus from which Saint Petersburg has grown into the present city. History buffs will adore it, and everyone will see amazing panoramic views from the top of its walls.