17 July 1918 and 9 November 1989. The Murder of the Russian royal family marked Russia's irrevocable move from a monarchy to a Communist state. Seventy Years later, the fall of the Berlin Wall symbolised the collapse of the ideology.

2 December 1942 and 26 April 1986. The first controlled nuclear chain reaction heralded the atomic age, but Chernobyl's runaway chain reaction was the first warning. How did the most exciting scientific breakthroughs ever lead to the disaster that the world had dreaded?