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.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The whole world in one water tank.

A museum dedicated to the quirky and colorful world created by Springfield's favorite son.

Experience the hysteria of a 17th century witch hunt through goofy reenactments and wax dummies that should probably be burned at the stake.

The pop art icon's gravesite is broadcast 24 hours a day on his museum's website.

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

A toxic ghost town sitting atop a massive coal fire.

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

There aren't too many operational funiculars around, but Pittsburgh has two!

The only way to see Pittsburgh is from the top of this lookout point, just like the ancient members of the native peoples did.

Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.

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.

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

A bit of retro transportation flair preserved in the world's largest department store.

Lie in a hammock where George Washington stood.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

Elevated freight railway turned wildly successful urban park.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

A Victorian park cemetery, standing on the site of what was once the Great North Wood.

An artistic tribute to the famous singer, just around the corner from where he was born.

Giant, friendly pelicans in Central London, the most unlikely of places.