The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

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

Decades before the scandal, this staircase on the river was a literal "water gate."

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

The oldest continuously operating fish market in the United States.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A historic neighborhood church is reborn as a psychedelic arts collective.

For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

A daily pyrotechnic celebration marks a beloved tradition during Valencia's festival season.

Two towns are linked by an engineering marvel masquerading as a boring suspension bridge.

Vibrant street art created with mixed media.

This massive fiberglass Gulliver turns every visitor into a Lilliputian.

This house's itty bitty size means no humans allowed.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

A 500-year-old series of tunnels long believed to be folkloric was uncovered beneath the streets of Puebla.

An indigenous take on European design creates a stunning visual overload.

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.