This Luxembourg cave is covered in cryptic looking marks left by mining activity.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

Kuwait City's uniquely designed water towers look straight out of a retro sci-fi cityscape.

The largest prehistoric ruins south of the Sahara, once a powerful center of international trade.

This peculiar lake of pitch is so thick and viscous that one can walk on its surface.

A gallery of underwater art that can be visited by man and fish alike.

The larger of two volcanic peaks rising out of the crystalline waters of the Caribbean.

Come for the springs; stay for the mud bath.

This large stone off the coast of Martinique had a brief career in the Royal Navy.

Thermal springs underneath the seabed provide the heat and bubbles for these beachside natural hot tubs.

This mountaintop lake bubbles and steams in a perpetual boil, thanks to its direct link to the Earth's interior.

Legend says those who drink from this trickle of water are destined to return to Montserrat.

A city continually buried under the ash of a volcano that has been erupting for more than 15 years.

Small church built in the 19th century for whites and slaves to worship together.

The shortest in the world, this landing strip stretches a mere 1,312 feet before steep cliffs on either end plunge into the Caribbean.

Commercial airplanes land mere feet over the heads of sunbathing beachgoers on this tiny island.

Millions of glowing microscopic organisms light up the waters of this luminous lagoon.

These eight mummies are the best-preserved human remains ever discovered in North America.

Greenland's first shopping mall also hosts the country's government.

1% of Greenland's entire population used to live in this single building, which is now slated for demolition.

This Norwegian satellite station provides ground services to more satellites than any other facility in the world.

This Arctic storage facility is a secure backup for agricultural biodiversity.

In the northernmost city in the world, it's illegal to be buried because it’s too cold for bodies to decompose.

This trio of Australian rock spires may have inspired aboriginal legend or just modern tourism.