France's national museum of scientific and industrial instruments.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

Visitors can explore the role of mysticism throughout the ages inside this interactive museum of magic.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

A floating cat sanctuary on an Amsterdam canal.

Started as a kitchen garden, now the second largest botanical garden in the world.

The block of aged dairy is probably still edible after 2,300 years in a peat bog.

After years of slow decline, a derelict Gothic castle is now being restored to life.

A harem-inspired Moorish fantasy design in a Victorian-era Welsh castle.

A subterranean playground in an abandoned slate mine.

Fantastically decorated underground chambers built in the 1760s.

Stonehenge has nothing on Castlerigg’s views.

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

A breathtaking flower tunnel bursts with beautiful golden blossoms.

The childhood home of Earth's alien chameleon is a humble Brixton flat.

Possibly the oldest of Britain's ancient henges is also one of its most stark.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

This picturesque view of the Scottish Borders was beloved by Sir Walter Scott.

This haunting stone chasm is a hotbed of mossy rock and English legend.

Three bridges straddle a stream, one stacked upon the other.

A house of bones — but nobody is quite sure to whom they belong.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

A mysterious pair of mice eating a piece of cheese is London's smallest public sculpture.

A mysterious monument where a woman who records say never existed was burnt alive for being a witch.