Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

At 16,627 feet above sea level, this unstaffed station is the highest in the world.

The world’s tallest outdoor lift stretches along the stone pillars that inspired the floating mountains in the movie “Avatar.”

Eurasia's most difficult place to hang out, and farthest point from sea access.

It seems that the residents of of this megalopolis suddenly vanished, but they were never actually there.

China’s breathtaking futuristic library is lined floor to ceiling with fake books.

This short pedestrian span is also known as the "Fairy Walking Bridge" because it looks almost magical.

Where the Great Wall of China meets the sea.

One of the world's largest ice festivals dazzles visitors for over a month with radiant sculptures and carvings.

The latest in a series of long glass bridges suspended at terrifying heights.

For those with no fear of heights: a skywalk 4,700 feet up on a Chinese mountain.

A total of 999 stairs lead visitors through a massive hole in a mountain known as the Gateway to Heaven.

This abandoned airplane hanger is said to have once been a top secret launch facility.

This top-secret nuclear bunker hidden in a Bosnian mountain has been converted to a modern art exhibition space.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

A war-torn Olympic relic is being overtaken by graffiti and nature.

Yugoslavia's biggest underground airport lies in ruins.

One of the longest wooden benches in the world snakes around Geneva's Treille Promenade.

A symbol of friendship between the mountainous regions of Switzerland and Bhutan.

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

A breathtaking bridge that crosses a vast gorge over a river's torrents, and has a tale of a devil architect attached.

The steepest classic funicular in the world glides along a dizzying incline.

This lovely little bridge hidden in a Switzerland gorge is essentially a fairytale.

These spooky and unusual stone formations create an underworldly landscape.