10. Heaven’s Gate, China
11. A huge water park, Germany
12. A door which can withstand a 30-megaton nuclear explosion
13. A radio-controlled truck
14. The Vajont Dam, Italy. It is 261.6 metres high
15. The quietest place on Earth: an anti-echo chamber. Here you can here the blood flowing through your veins in your head
16. A machine-gun post dating from the Second World War, France
17. A baby dik-dik
18. Aerogel: a synthetic material which is 99.9% air
