An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

Go take a picture with the inventor of the daguerreotype photographic process.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

D.C. once had its own tiny rival to the New York Stock Exchange.

Where the U.S. government kept its actual treasure, before Fort Knox.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

The oldest Roman lighthouse still in use.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

This cemetery features modernist statues as strange as its name.

A beautiful but toxic fountain of mercury.

This semi-secret storybook hedge maze is also the oldest garden in the city.

The final resting place of the great navigator, or maybe his brother.

Bacteria and algae give the salty water its bubblegum hue.

An abandoned Indian-inspired mansion.

Beneath the city of Lourdes, France is a massive, concrete church.

Of the many chalices in the running for the Holy Grail, this one in Valencia Cathedral sure looks the part.

Houses are tucked between, on, and underneath giant boulders.

An arresting arch punched straight through a mountain provides one of the most scenic spots, and challenging climbs, on the planet.

This century-old ruined temple was reborn as "The Church of Skate."

Two large posteriors in one giant statue.

Stormy conditions send jets of seawater bursting through holes in the cliffs.