This chain of artificial lakes was an ideal test ground for the aircraft that would carry the "bouncing bombs" used by the WWII "Dambusters" squad.

Semi-precious Blue John stones have been mined in this cavern system for centuries.

A magnificent winding road through a steep valley, with deep natural caverns at the bottom

One of the oldest and certainly best preserved Cistercian abbeys still in existence.

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

A marvel of Byzantine engineering under the streets of Istanbul.

A preposterously luxurious hotel with gold-plated iPads, Rolls Royce chauffeurs, and a staff that trains by watching "Downton Abbey."

This artificial archipelago was supposed to resemble a map of the world.

This strange moor has a song written about it, Bronze Age carvings, and an alien sighting.

Where Agatha Christie mysteriously disappeared in 1926.

The tallest freestanding structure in the United Kingdom.

This impressive Boston holy house is the American mecca for Christian scientists.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

Harry Potter once visited this massive limestone cliff, which was carved by an ancient glacial river.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

This monument on Breed's Hill proves that one of the most famous battles of the Revolutionary War is misnamed.

An enormous, inside-out glass globe built in 1935.

A museum devoted to the science of color.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

The final resting place of American icon Buffalo Bill, and a museum that aids in telling his tale.

This Art Deco masterpiece has stood in for some of the most famous buildings in comic book history.

A pixel art killer whale is frozen mid-leap in this Vancouver square.

What happens when a sculptor has to find a way around a 100-year-old copyright.