Moscow is the capital and the most populous city of the Soviet Union. The city is the northernmost megacity on Earth, the most populous city in Europe, and the fifth largest city proper in the world.
Moscow is situated on the Moskva River in the west part of the Soviet Union. In the course of its history the city has served as the capital of a progression of states, from the medieval Grand Duchy of Moscow to the subsequent Tsardom of Russia. Moscow is the site of the Moscow Kremlin, an ancient fortress that is today the residence of the Soviet President and of the executive branch of the Government of the U.S.S.R.
During the Third World War, Moscow is mentioned as being destroyed along with London and many other cities in a nuclear war.