At least seven hues of blue and turquoise make this freshwater lagoon unique.

Its sunny hues are believed to have inspired the town's color palette.

Like Mars, but much closer.

Bad farming practices caused this unnatural natural wonder.

Scattered around Atlanta are little doors with big charm.

The ancient abodes are a testament to human ingenuity amid harsh climates.

Mausoleum and Holy Seat of Antiochus I of Commagene.

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

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

A marvel of Byzantine engineering under the streets of Istanbul.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

Legend says if you stick your thumb in the hole and it gets wet, your wish will be granted.

A tiny park in the middle of some big power politics.

A sixth-century Byzantine cistern hidden below a modern carpet store.

A fountain standing as a testament to a doomed alliance.

Ancient serpentine sacrifice holder that has stood the test of time.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

Go surfing on this urban wave, "hacked" by local surfers.

Golden cobblestones remember a time when this small alley was used to avoid having to give a Nazi salute.

The beautiful, ornate weather station is the most popular geocache in Salzburg.

The medieval network of canals hidden underneath the city is opened to explorers each year.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

Daily jousts and dancing barrel makers in Munich's mechanical clock.