A little-known subterranean street runs under some of the best-known buildings in Chicago's River North.

A gothic church spire sits atop this skyscraper, the tallest church in the world.

Ancient petroglyphs discovered only after a massive fire swept across Michigan in the 1880s.

Turnip-shaped island just off the Michigan shore in Lake Huron.

House built with over 60,000 glass bottles.

This shallow cave got its name from copious amount of human bones found inside.

Watch the ships come in on Michigan's 210 ft. high observation deck in Sault Ste. Marie.

This lighthouse and shipwreck museum keep a torch burning for the memory of the SS Edmund Fitzgerald.

Reason for Michigan's potential diamond mine.

This freshwater spring fills with 10,000 gallons of water per minute.

Just below the surface, shrimp are producing temperatures hotter than the sun.

Decorative shell walls built in the 1940s sit atop an ancient midden created by the Calusa Native Americans.

An abandoned vacation home spent a decade taking on legends. It's now taking on water.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

A perfect circle of twenty-four mysterious holes dates back to prehistoric time.

When this test site was abandoned, they didn't even bother to take the rocket with them.

The museum chronicling a treasure hunter's dream, fulfilled.

The bottle house obsession struck a Florida man in his retirement, and now he can't stop building.

The scuba diving training facility was named for the steam that rises from the cave's chimney.

An eclectic treasure trove of maritime marvels.

A steamer run aground near Bimini lives a second life as a playground for scuba divers.

An underwater statue of Christ blesses the depths off Key Largo.

The subtle science of a master molecular gastronomist.

This grand old 80-foot sequoia towers above the buildings in the city’s retail center.