A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

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.

This monument on Breed's Hill proves that one of the most famous battles of the Revolutionary War is misnamed.

By day this New Orleans square is for pedestrians, but by night it is a kingdom of kittens.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

The farm where one of America's greatest leaders was raised is now a well-appointed landmark.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

California's own majestic geyser is powered by a subterranean volcano.

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.

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

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

Louise Bourgeois' 30-foot-tall steel spider sculpture.

A surviving remnant of the thick ice mass that once mantled most of Western Canada's mountains.

Few other hotels can rival the grandeur of the Castle in the Rockies.

One of two side-by-side totem pole parks dedicated to educating visitors on Tlingit history and culture.

The king of U.S. high points towers over every other peak on the continent.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Scattered throughout London are ancient remnants of the city's former bounding wall.

Hear the quietest sound from across the dome.

Museum celebrating the history of computers, especially their role in codebreaking.

A harem-inspired Moorish fantasy design in a Victorian-era Welsh castle.

One of Europe's oldest libraries.

Famously misunderstood wonder of the ancient world