NB: Smith is not responsible for any cases of vertigo, dizzy spells or rushing adrenaline caused by these images.

Whether you fancy yourself a mountaineer or you just like climbing trees - this challenge is not for the light-hearted/weak-limbed. Dauntingly called 'The Excalibur', the rock-climbing wall is the world's largest freestanding one-of-its-kind, soaring to a whopping 37 metres. You'll have to travel to the Netherlands to have a crack (where ironically the land is as flat as a table), but we'd recommend working up to it on something closer to the ground.