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

It was originally part of a "terrible lizards" collection at the 1964 New York World’s Fair.

An avant garde art museum at the University of Chicago.

A hidden grotto on the grounds of the Kane County Government Center.

The final resting place of the world's first nuclear reactor.

Urban explorers embraced America's now demolished first suburban mall, south of Chicago.

An unlikely Transcendental Meditation haven in the American Heartland built around the ancient Vedic principles of balance and harmony.

What was once the second largest steel mill in the US is now a sprawling complex of modern ruins.

This grave marks the final resting place of a legendary frontiersman... unless it doesn't.

This huge clock made of flowers and simple machinery was once used a political weapon.

Low-frequency noise compared to an idling train can only be heard by some of this industrial town's residents.

A cemetery for only coon hounds in northwest Alabama.

Once adorning a New York skyscraper, these reclaimed ruins now haunt an Indiana park.

This elaborate estate contains a stunning marble aviary, a sunken conservatory, and a magnificent music room with a two-story pipe organ.

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

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

An unknown number of cholera victims are buried in two nondescript graves.

One of the few surviving "Wigwam"-themed motels.

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

The small cave that housed Tennessee's "first citizen."

If astronomy had a ghost, it would look like this observatory.

Ornate limestone building now filled with geologic specimens, and more.

One-layer pyramid in Indiana.

The juke joint where legendary soul artists ate, drank, and made merry.