Max Pearson presents a collection of this week’s Witness History episodes from the BBC World Service.

Our guest is Dr Lara Douds, Assistant Professor of Russian history.

We start in 1907, the men who would go on to lead the Russian Revolution met in London for a crucial congress marking a point of no return between the Bolsheviks and the Mensheviks.

Then, in 2000, the launch of Steel Dragon 2000 at Nagashima Spa Land in Japan, becoming the world’s longest rollercoaster at nearly 2.5 km in length.

Next, the political assisination of Juan Mari Jauregui, a retired Spanish politician and long-time campaigner for independence, by Basque separatists in 2000.

Plus, how in 1986, during a world record attempt and publicity stunt, one and a half million balloons were released as a storm rolled over the city.

Finally, the story of Chuquicamata, Chile’s abandoned mining town after its 25,000 residents left due to pollution concerns .

Contributors: Henry Brailsford - British journalist Dr Lara Douds - Assistant Professor of Russian history Steve Okamoto - rollercoaster designer Maixabel Lasa - widow of Juan Mari Jauregui Tom Holowatch - project manager of BalloonFest '86 Patricia Rojas - former resident of Chuquicamata

(Photo: Lenin giving a speech in Red Square. Credit: Universal History Archive/Getty Images)