Sections of the iconic limestone columns have been left uncleaned as a reminder of the city's polluted past.

These disused steel furnaces are now haunting ruins that may one day be a national park.

A giant ball made from pieces of an old Jeep.

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

The world's largest military aircraft cemetery.

The oldest experimental corn field in America is still creating better ways to grow crops.

What was once the largest NFL stadium.

World's largest Christmas store.

Everyone's invited to put on a miniature concert with this world-class musical wonder.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

No one knows how many bodies are in this vault in a Chicago public park.

G.V. Black, the Father of Modern Dentistry, keeps an eternal eye on Chicagoan’s teeth from his perch in Lincoln Park.

Could it have picked a better place to land?

One-of-a-kind museum inside the first Boeing 747-400 ever made.

Two Civil War-era cemeteries stuck between runways at the world's busiest airport.

3/4-scale model of the White House in Atlanta, Georgia.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

Chicago's Navy Pier on Lake Michigan was a training hub for aircraft carrier pilots during WWII.

The palatial McDonald's that inspired Wesley Willis.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

10,500 square feet of pinball housed in former dollar store and home to the last playable "Thunderball."

Thousands of people walk over this fantastic work of art every day, but how many notice it?

A restored Pittsburgh house of God has been converted to a marvelous house of suds.