A subterranean world of tunnels links several buildings of this rare 19th-century asylum.

Dating back to the 1800s, two imposing buildings in Michigan have had countless transformations over the years.

The world’s largest Masonic temple was saved by the White Stripes.

An eccentric inventor's castle home with its own indoor weather system.

Unlike other abandoned asylums this empty institution welcomes visitors, just don't go in the buildings.

The bears may be gone, but their old cages can still be found.

This miniature feudal castle was built on a whim to honor a US Navy pioneer.

A spooky and decrepit mental health facility is slowly being replaced with newer digs.

This Dutch-styled residential building was originally a cocoa company's World's Fair showpiece.

This decrepit abandoned building is made all the more eerie by its dark history.

This stone tower in a small town's graveyard looks as though it would be more at home in a fairy tale.

This beautiful architectural gem was the first waste treatment facility in Boston.

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

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

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

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

This stunning gothic ruin was a casualty of the Indiana steel industry crash.

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

A flamboyantly decorated bridge signals diversity and fellowship at the entry to Indianapolis' Broad Ripple Village.

The bespectacled, cocktail-sipping pachyderm is a strange but fitting liquor store mascot.

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

The grave of the iconic Kentucky Fried Chicken mascot features a bust of the man behind the goatee.

The only building in Louisville (hopefully) that contains two ancient holy skeletons.

The world's oldest and largest museum of mass transit vehicles.