A flooded Mexican cave that hides a river beneath the water.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Hot Doug's "Hot Dog" Stand.

An unassuming store hides relics of its former life as the jazz club that hosted some of the best black performers of the 1920s and '30s.

A theater sits abandoned on Roosevelt Road, once majestic in splendor, now majestic in decay.

The palatial McDonald's that inspired Wesley Willis.

A Museum of Holography frozen in 1974.

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

Landmark Chicago building narrowly avoided destruction.

A long lost multi-cultural music venue used to reside in the bottom floor of Chicago's Flat Iron Building.

A curious collection of miniatures in a quiet corner of the Chicago Children's Museum.

Odd, decrepit fountain honors Chicago author who had mixed feelings about his hometown.

Huge abstract sculptures of the Puerto Rican Flag.

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

These chunky stone towers out in Lake Michigan are the key to Chicago’s drinking water.

You can take a class, browse the library, or visit the lavish lair of an international men's humor society.

Illegal drag racing two stories beneath Chicago’s streets.

The oldest house in Chicago certainly doesn't look the part and there are some who say it doesn't deserve its title either.

A Chicago Movie Palace Lost to Time.

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

A goddess-topped water fountain in Chicago was created thanks to the dreams of a thirsty newsboy.

This alley in downtown Chicago held the bodies of over 600 people after the fateful Iroquois Theatre fire.

Once called the "Polish Gold Coast" it is an icon of the neighborhood that bears its same name.