The maximum security facility was once thought to have "the bloodiest 47 acres in America."

The house where the famed outlaw was shot by a dirty coward is now a museum to the criminal's legacy.

The history of the treatment of mental illness, illustrated in all its gory detail, and housed in an asylum.

European castle ruins in an American state park are actually the product of death and grief.

The only Bahá'í house of worship in North America and one of only a handful worldwide.

Nonprofit art center that promotes outsider, intuitive, and self-taught art.

A Bibliophile's Dream.

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

A half-mile long and three stories high, this bridge over the Des Moines River Valley mimics a descent into a mine shaft.

The haunting ruins of a military fortress turned astronomical observatory sit on a Sarajevo mountaintop.

The longest navigable underground river in the United States is home to countless blind and albino animals.

River pirates, murderous bandits, and serial killers used this Illinois cave as their debauched hideout.

Curious cave that stays a cool 56 degrees all year long.

Giant granite rocks standing end-to-end like a train of circus elephants.

In the St. Francois Mountains in the Ozarks at 1,772 feet above sea level, Taum Sauk Mountain is the highest (and possibly oldest) peak in Missouri.

A chessmaster's dream destination.

A historic house in St. Louis was plagued by a series of suicides committed by family members involved in a successful brewery.

An enormous natural sandstone bridge in Kentucky.

Erosion and time have created a naturally-formed water park.

A museum dedicated to man's boldest venture.

This life-size bronze statue remembers the tallest recorded human in his Illinois hometown.