Three bridges straddle a stream, one stacked upon the other.

The ancient latrines of the Greeks, in all their public glory.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

A rocky sea serpent hides caves, blowholes, and a spectacular natural bridge.

A fifth-century temple improbably built into the side of a cliff.

Home of the world's largest crocodile.

The tallest sea cliffs on the Southern Hemisphere are a climber's worst nightmare.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

A small man-controlled waterfall powers an Art Nouveau elevator and is accessed via narrow gauge, solar-powered tramway.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

Tiny Swedish village with a distinct local phenomenon known as an "Elk Shower."

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

Bermuda triangle lighthouse, site of mysterious disappearances, left to crumble into the Atlantic.

A lake at the bottom of the ocean.

Spirits from these lakes are said to produce the local weather and odd phenomena as they bicker between themselves.

Huge hole looks down onto an underground beach populated with sea lions.

A sacred lake with thousands of sacred carp and a biblical history.

A beautiful geyser under environmental threat.

England's most notorious suicide spot.

World's strongest whirlpool.

An ethereal glowing blue ocean cave in Croatia.

An underwater restaurant, surrounded by a coral reef.

The remains of what was, not so long ago, the world's largest city.

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