These former Nazi anti-aircraft towers offer a singular view of the north of Berlin in the summer, and a sanctuary for bats in winter.

An all-female order shares an ancient culinary art with visitors at their mountaintop monastery.

The largest bottled beer collection in the world holds over 22,000 unique beer bottles.

This ancient Silk Road outpost overlooking the Wakhan Valley is miraculously still standing.

Norway has built what may be the world's most beautiful public toilet.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

An abandoned network of military bunkers and tunnels open for anyone willing to descend into the darkness.

This "floating railway" is one of the world's oldest monorail systems.

A massive wintry wall of snow up to 66 feet tall flanks a highway through Japan's mountains.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

An elegant chandelier hangs over this ancient sewer chamber, now open for concerts and public tours.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

This plot of old-growth forest is the largest surviving remnant of New York City's original woodland.

Travel through the hidden underbelly of the city in colorful tunnels filled with art and history exhibits.

A 1,500-year-old, 3-story subterranean city where ancient Persians took refuge in times of war.

This isolated structure beckons adventurers with sublime views of the Faroe Islands.

The medieval home is still engraved with the symbol of the profession, an eye flanked by two axes.

This historic motel standing at the "crossroads of America" offers a radio in every room and was saved by local protesters.

There is only one place in the world where the corners of four nations come together.

The 20-mile causeway that separates the Netherlands from the sea.

Intensely colorful calcite pools in Southern China.

An ancient stone fortress considered by many to be the eighth wonder of the world.

Stenciled handprints and wall paintings dating back 10,000 years, some of the earliest forms of cave art.

Where better to stay the night than inside a trio of ancient Chinese deities representing "the good life."