This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

A little sculpture with a large wardrobe.

Climb inside an iron crystal magnified 165 billion times its normal size.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

An imperial fortress city that incorporated cultural elements from the entire Mughal empire, only to be abandoned the year it was finished.

An ancient iron pillar in Delhi that seems to be rustproof.

A blooming house of worship for the masses.

An extraordinary "City of Caves" carved from solid stone.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

The 953 windows undoubtedly make this the world's most beautiful screened porch.

Once an indicator of social class, the color blue has come to define this city on the edge of the Thar Desert.

Northern Ireland's Brobdingnagian stepping stones.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

This short bridge is the only thing connecting a tiny Irish island to the mainland.

Carvings in Turkey's Marble Road may have directed ancient Romans to a hidden brothel.

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

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

1513 Turkish world map, full of European state secrets and snarky commentary.

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

A Lycian city of the dead carved into the hillside of Southern Turkey, complete with startlingly human touches.

This famous city eluded concrete detection until the early 2000's.

A marvel of Byzantine engineering under the streets of Istanbul.

Roman ruins top white travertine terraces formed by ancient hot springs.

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