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

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

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The walls of the iconic dome are hollow and have a secret stairway.

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

Home to items never before seen by the public.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

The oldest active church in Pennsylvania is also the second oldest Swedish Church in the United States.

Golden and naked, the figure that was once the highest point in New York is all that remains of the second Madison Square Garden.

Alexander Hamilton’s creation caused quite a bit of controversy.

A daily replay of the experiment that proved the rotation of the Earth.

This elaborate towering structure was once famed for its revolutionary height.

Yo, Adrian!

Ant sculptures march up the side of what used to be an iconic spot in punk rock lore.

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

Lucerne's central prison was converted into a tourist hotel with a bare minimum of changes.

This historic covered bridge contains a series of macabre paintings that communicate one thing: everyone dies.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

Two stone columns flank the grand Venice square, but there were supposed to be three.