A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

There’s a hidden military meme engraved on the World War II Memorial.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

Home to items never before seen by the public.

A museum dedicated to exhibiting remarkable outsider art.

Color-coded signs direct drivers on a network of routes designed to avoid Pittsburgh traffic.

A portion of the old Pirates stadium over which a defining home run once flew still stands even after the rest of the stadium was torn down.

Meet your friends, marry your true love, or tell your enemies to kiss your butt under this historic Pittsburgh timepiece.

A model of a dinosaur that was named for Andrew Carnegie stands outside the museum that also bears his name.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

A drab two-story office space in Delaware is a hidden tax haven for Hillary Clinton, Donald Trump, and over half the Fortune 500 companies.

A blend of art, antiquities, and Americana fill this museum, surrounded by whimsical, enchanting gardens.

A scenic fort on the harbor protected Philadelphia from an attack that never came.

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

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

Yo, Adrian!

A series of abstract, silly sculptures represent the works of a great modern classical composer.

This bridge was constructed from the rubble of the infamous Bastille.

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

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

Indents in the pavement are all that remain from a grisly death machine in Paris.