Ukraine is the second largest Eastern European country (after Russia), and was formerly an important constituent part of the Soviet Union, before becoming independent after the latter's collapse.
During Soviet times, the town of Pripyat was built to house the workers of the nearby Chernobyl nuclear power plant. In 1986, Chernobyl staff were carrying out tests on self fuelling reactors. Technical problems arose and reactor No4 exploded, an explosion worse than 400 atomic bombs. Thanks to quick firefighters, a 2nd explosion was averted that would have wiped out half of Europe. Soviet nuclear plants were built without a cover so there was no containment dome to stop deadly nuclear radiation from leaking out. Pripyat was rapidly evacuated, while "liquidators" worked on building a "sarcophagus" over the reactor ie a dome to cover the 17 millions of nuclear waste; a process which took decades. The abandoned Pripyat nowadays stands frozen in time, looking like the set of a post-apocalyptic horror film.
Kiev ("Kyiv" in Ukrainian spelling) is one of the grand old cities of Eastern Europe. Its history spans over a thousand years, during which it has been part of changing empires, hence boasting glistering monasteries and churches, as well as Soviet architecture. It's a good mix of east and west, the only big minus: you don't want to be there from mid October to mid April.