Sleep in the cockpit of an old plane or a train stopped on a bridge, spend the night in a transparent capsule on the side of a cliff, in a secret contemporary art work, in an old church or a house perched on top of a water tower, treat yourself to a night in an igloo, a circus or a futuristic house hung in a tree, in an underwater room or an open-air suite. Hotels are sometimes destinations in their own right. To make sure you have a holiday that is truly out of the ordinary, we have taken great pleasure in identifying and testing more than 50 unique hotels around the world in some thirty different countries.