The Soviet Union was the largest country ever, a superpower.
After surviving World War II, the USSR put the first satellite in orbit (1957) and the first man in space. They matched the US in development of nuclear weapons, and pioneered peaceful nuclear power plants. But in 1986 one Soviet reactor, Chernobyl, suffered a total meltdown, the worst nuclear disaster ever. Shortly after that, the Soviet Union disintegrated.
Russia retains most of its territory, people, and power; but most of the smaller republics in Eastern Europe have westernized, some even joining NATO and the European Union.
By 2016, the Chernobyl reactor was set to be entombed forever under an expensively built New Sarcophagus. In Moscow, Soviet space monuments now represent rockets that carry Russians and Americans too into space.
A quarter century after it ended, what of the Soviet Union is left?