This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

The only female equestrian statue in Washington, D.C. is a 15th-century French heroine.

Over the last century, this elegant columned facade has been home to the headquarters of a bank, several nightclubs, and a restaurant.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

The hippo that stands on this university campus was once a drunken flea market purchase.

One of the first Second Empire-style buildings constructed in North America.

The only Leonardo Da Vinci painting in the Western Hemisphere.

The story behind this beloved toy—named for Theodore Roosevelt and owned by his grandson—is more complicated than you might guess.

A public art jibe at one of the United States’ oldest and longest-serving senators.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

The 28,000-year-old specimen is remarkably intact.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

This forgotten boat elevator was an engineering marvel in its heyday.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

This poor little statue is the most vandalized memorial in Washington.

The span is crooked and made from two older recycled bridges.

The house where John Wilkes Booth conspired with his co-conspirators.

A computer bug so primitive it was an actual insect.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.