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

The first declared National Monument in the United States.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

Yo, Adrian!

Daily jousts and dancing barrel makers in Munich's mechanical clock.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

A monument celebrating the idea of reaching inaccessible places.

World's first "penitentiary," meant to be humane, drove men insane.

A little sculpture with a large wardrobe.

The fairy tale castle of the "fairy-tale king."

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

Famously misunderstood wonder of the ancient world

The celebrated eyesore created by starry-eyed sweethearts.

Elevated freight railway turned wildly successful urban park.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

An outlandish shoe shaped house built by an eccentric millionaire.

A local prank turned town icon.

These tourist trap caverns are said to be the former home of a legendary Pennsylvania Hermit.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.