A relic of the Cold War in Chicago.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

This upscale streetwear store is hidden behind a fake Snapple machine in the back of a deli.

19th-century operating theatre in which the use of ether was first demonstrated - plus, a skeleton and a mummy!

A small abandoned and abused cemetery that has become a magnet for ghost hunters.

A shining sculpture made of 3,115 lights, the number of visible stars in the Northern Hemisphere.

Once at the center of U.S. finance, the historic Trading Room was meticulously recreated piece by piece and rebuilt in the Art Institute.

The legendary building that needed ghostly approval before being built.

This weird abode has inspired everything from the "House On Haunted Hil" to a robot hunter's pad.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

Not to be confused with the iconic New York City skyscraper, this Chicago building is a vibrant hub for artists.

Orthodox church partially financed by Tsar Nicolas II.

An abandoned meat mecca now serves as an excellent locale for urban exploration.

A century-old network of freight tunnels underneath the city's historic business district.

The last masonry skyscraper ever built reveals a transitional moment in architectural history.

The famous Beatle secretly visited this Illinois town several times to visit his sister.

Tucked away amongst townhomes lies a restored, early 20th-century tea house and garden, the only remains of a historic estate.

The murals have transformed a residential alley into a vibrant drive-through gallery.

A former atom smasher turned into an art gallery.

Now nearly abandoned, Kaskaskia was once the capital of Illinois and one of the most important towns on the upper Mississippi.

A mini Wrigley Field for mini baseball players.

A historic and oft-filmed prison stands in a Chicago suburb.

Built in 1869, this now-retired structure looks more like a medieval fortress than a county lock-up.