Réunion Island's highest point is a 2 million-year-old volcano and a paraglider's paradise.

This imposing tower named after the mythical sword of King Arthur is considered the tallest freestanding climbing wall in the world.

Traversing steep Alpine slopes, this engineering marvel is one of the longest and highest funiculars in the world.

In a city that boasts four separate inclined cable railways, this is one of the busiest funicular lines in the world.

Caves full of Buddhist statues, incredible rock formations and a deserted lagoon.

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

A subterranean playground in an abandoned slate mine.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Home to secret Eastern Bloc spy equipment and the largest stretch of the original Berlin Wall outside of Germany.

Home to items never before seen by the public.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

This small exhibition displays equipment and artifacts once belonging to the feared Stasi secret police.

This shop for all your super spy needs hides an educational secret.

This monument sits at the foot of a mountain from which legend says enslaved people jumped to their deaths.

The world's biggest pet store.

A masterpiece of LGBT art has been restored in what may now be the most valuable restroom in America.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

The barrel-made lookout from Shackleton's final ship is tucked away in the crypt of one of London's oldest churches.

A collection of 4,000 thimbles that's more versatile than one might imagine.

This historic Chilean cemetery is the burial place of hundreds of European and American freethinkers and non-Catholics.

You can still ride this 100-year-old work of art in Brooklyn's largest public park.

Hidden in a metro shop under a shopping mall, this small museum tells the story of one of the world's largest urban transit systems.

This small museum displays a collection of outsider art and scale models of past "treatments" for mental illness.