A lesser-known part of the Kinsey Institute is this impressive collection of art, artifacts, and material culture related to human sexuality.

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

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

One-layer pyramid in Indiana.

Tucked away in the forests of Indiana resides an abandoned waterslide that is now a popular graffiti haunt.

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

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

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

Inside, ancient treasures. Outside, modern contradictions.

What is it about mushrooms that makes people wish they lived inside of them?

This humble star-gazing center touts itself as the "Birthplace of American Astronomy."

Where beautiful signs live on forever.

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

An obsolete, vanishing traffic device warns Cincinnati drivers away from middle-of-the-road obstructions.

A ship that lived many lives under many names is now known merely as the "Ghost Ship."

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

The massive, original Colgate Clock is mounted on a defunct factory building that was once a prison.

This 19th century mansion façade adorned with immigrant patriotism is a symbol of Louisville’s history.

Unique tower has outlasted a takeover of the company.