A hollow cement depiction of time's inexorable effect on the human body.

A turn-of-the-century architectural marvel built on healing mineral springs and salt licks.

A castle built by an eccentric medieval enthusiast in rural Ohio.

The only freestanding table rock formation east of the Mississippi.

A suspended garden, now gone, once hung in the middle of this abandoned church.

An abandoned relic of the city's failed experiment with below ground transit.

A memorial for an outsider theorist who believed that the planet is actually hollow.

A stunning, abandoned limestone quarry in southern Indiana provided the stone to erect the Empire State Building.

One-layer pyramid in Indiana.

One of the first historical sites of an alternative universe was installed in the town of Paris, Illinois—which is now home to an annual spelling bee of Kcymaerxthaereal words.

One tree's homage to soles past and present.

A 30-year-old Sycamore tree grown from a seed taken to the moon and back.

The body of one of the world's most famous outlaws is covered in cement and iron to prevent it from being stolen.

A collection of relics from the Spiritualist Camp Chesterfield.

A hidden network of subterranean passageways lies tangled beneath Indianapolis' bustling City Market.