Decades after testing the polio vaccine on unwitting patients, this historic mental hospital sits in ruin.

These decaying bridges 1,000 feet high are a reminder of the skill it took to cross the Colorado Rockies by rail.

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

This once-popular otherworldly landscape was formed by one of the largest volcanic eruptions in history.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

South Carolina's last remaining slavery auction house is now a museum devoted to its own tragic history.

One of the Eight Wonders of Kansas and the first official National Natural Monument these stark formations look like nature's Stonehenge.

This Memphis recording studio launched the careers of Jerry Lee Lewis, Johnny Cash, and Elvis Presley.

The end of the 4 Line is also the end of the line for 300,000 souls in one of NYC's most illustrious cemeteries.

A sliver of nostalgia in Seattle's Viretta Park.

This amazingly preserved Gold Rush town is a historian's dream.

A mine fire has been burning under the deserted town since 1962, but this church is still going strong.

Beyond the usual stories that attend old prisons, this one has deep bloody undercurrents.

A replica that won't float away.

This large midwestern cavern features impressive rock formations and an underground waterfall.

Hell on Earth is actually a small town in Michigan where anyone can be mayor for a day.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

A number of gruesome unsolved murders have turned this simple home into a morbid tourist trap.

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

The hotel where Martin Luther King Jr. was shot is now a museum dedicated to his work.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

These towering spires and glowing walls are carefully crafted from hundreds of thousands of icicles.

The perfectly named cave drop is the deepest in the continental United States, almost matching the height of Seattle’s Space Needle.

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.