This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

Bridge that died in war and was resurected.

The highest point in Belgium is a staircase to nowhere.

Hiding the longest subterranean river known in the world.

Where beer lovers can literally immerse themselves in beer.

A naturally beautiful, seemingly bottomless deep blue spring.

A medieval bridge stretches over a sulfur-rich river that leads to year-round natural hot springs.

Iran's colorful terraces are a rare geological masterpiece.

World's strongest whirlpool.

The youngest volcano in Central America.

Volcanic activity causes small pools of super-heated mud to boil furiously.

This neon blue river gets its color from a unique mix of bacteria and volcano minerals.

The sister plane of the C-123 shot down during the Iran-Contra Affair has found a new purpose in retirement.

Costa Rican accommodation resembles a crash site, but with a nice balcony.

Right angles in the forests of Panama.

The rusting hulk of a hand-powered, nearly 160-year-old submarine abandoned in 1869 due to the ravages of decompression sickness.

These giant volcano sponges in Antarctica are thought to be the world's oldest living animal, at 15,000 years old.

Southern Ocean waters and glacial forces transform the Antarctic ice into these stunning bridges and caves.

An abandoned whaling station on an active volcano offers hot springs in Antarctica, surrounded by ruined giants of industry.

Massive sinkholes on a mountain in one of the most remote places in Venezuela.

This everlasting lightning storm may be the world's largest generator of ozone.

This "floating island" plateau sits 7,671 feet above the forest floor.

These mammoth-yet-narrow crevasses in the Earth are perfect for taking an otherworldly swim.

One Costa Rican island is so beset by illegal shark poachers that the local rangers have built an entire bridge with their confiscated gear .