Wild lights and sound effects turn a walk through some caves into an eye-popping 1960s tourist attraction.

One part antique store, one part curiosities hodge-podge.

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

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

Ride the subways of yesteryear.

The remains of a failed attempt at medieval nerdery are hidden deep in the woods of Virginia.

Continuing the tradition of the dime museum in style.

Giant busts of 42 U.S. presidents are sitting in a field in Virginia.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

An emerald-green grotto just a short trip from Austin.

One person's lost luggage is another person's treasure.

Left untouched since a double murder-suicide in the 1960s, Los Feliz murder mansion remains a neighborhood mystery.

San Francisco's newly reopened hands-on science museum.

Rainbow-hued local gem in Venice.

An underwater city for the dead.

This unique structure in suburban Austin is made up entirely of other people's castaways, and constantly changing.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

Hollowed out cedar log tubs set in an ancient towering forest.

Just a few miles from downtown Atlanta is a trail covered in a crazy collection of outsider art.

A "gravitational anomaly" located in the redwood forests just outside of Santa Cruz, California.

The first declared National Monument in the United States.

Odd outsider art installations surround a Gold Rush-era ghost town.

A hand-built folk art installation covered with messages of God's love.