TV Presenter Chris Tarrant travels around the world to ride some of the most extreme railways that wind their way through some of the harshest terrain on Earth. Eps:

CONQUERING THE ALPS: Chris crosses mountains, deserts, jungles and war-zones to discover how railways have been central to to the history of 4 very different parts of the world. He begins with a journey across the Alps, starting in Vienna.

THE TRAIN IN SPAIN: Chris embarks upon a 1,000 mile journey across Spain discovering how the railways were involved in tensions over Gibraltar, the Civil War and WWII. But Spain has quietly become a world leader in train technology.

*EXTREME NUCLEAR RAILWAY:** A JOURNEY TOO FAR? Chris travels across Ukraine, taking in some of the country's 13,00­0 miles of railways. Along the way he takes in Kiev and Chernobyl, finishing by the banks of the Black Sea in Odessa.

THE REUNIFICATION EXPRESS: Chris embarks on a rail trip across Vietnam, exploring its French colonial history along the way, as he sets off along the Reunification Line from Ho Chi Minh in the south – to Hanoi in the north.