2. Mission: Space

We aim for the stars and find out why unwanted battleship guns allow the United States to gain vital information about the borders of space. We ask how the shattered remains of a secret Nazi base became the first on the path to a new world, with the development of the ground-breaking V2 rocket. We explore a forgotten structure deep in the Arizona desert to ask if it is the true home of America's space programme. And we reveal the bizarre link between a discarded oil drum and a Cold War struggle to survive in zero gravity.

3. Lost Bridges

Soaring across some of the widest rivers and deepest valleys on the planet, bridges have always been at the cutting edge of engineering. We travel high into the mountains of the Colorado desert to find out why a hidden engineering masterpiece could disappear at any time. We ask why a stretch of overgrown concrete in a Czech reservoir is known as 'Hitler's bridge'. We find out how the highest bridge in the world collapsed in less than one minute. Finally, we uncover the story behind Cape Town's invisible bridge, which never carried a single vehicle.

4. Ghost Ships

Exploring ship graveyards, including Scapa Flow in Orkney, where German warships were scuttled after the First World War, and Mallows Bay, home to 200 wrecks colonised by wildlife.

5. Quest for Power

How Europe's most advanced power station became a film set. Plus, the structures made by scientific pioneer Nikola Tesla in his thwarted quest to prove the US with free electricity.

6. Roads to Nowhere

Hear how a crumbling hill in the Peak District and dunes in California caused the closure of two roads. Learn why a route used by the French Resistance shut in 2003.