Capital Gate, Abu Dhabi – the most acutely leaning building in the world. It bows out 18 degrees from the vertical – in comparison, Pisa’s famous tower is only leaning at 3.99 degrees. Technologically ambitious and architecturally stunning, it looks like nothing on earth. (Well, okay, it does look like something in particular, but this is a family-friendly corner of the Web and we refuse to draw certain parallels).