The Sky Pool at Embassy Gardens in London, England

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A swim in the sky

A lap in this 'sky pool' may have you holding your breath, and not just because you're underwater. With the streets of London looming 10 storeys down, the view through the pool's clear bottom is a bit freaky to all but the fearless. But swimming here is a one-of-a-kind experience, and for some lucky residents of these twin apartment blocks near the U.S. Embassy, a convenient way to pop in on neighbours the next building over.

The pool is suspended 35 metres in the air, but its origin is even loftier: It was manufactured in Grand Junction, Colorado, to be precise—then shipped across the pond to its new home in London.