These beautiful ruins deep in the Pennsylvania woods are thought to have been a ski lodge or a speakeasy, but no one really knows.

A beautiful oddities shop crammed with strange and morbid curiosities.

Explore 10 acres of environmental sculptures.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

A once-booming Mississippi River town with a history of racial violence is now eerie and mostly abandoned.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.

Found art has transformed this Pittsburgh neighborhood into a psychedelic dream.

A colorful architectural gem in Seattle's uniquely modern Central Library.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

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

Crammed into a Baltimore row house is an oddities shop that sells everything from skulls to dead insects.

Mysterious 500-year-old tapestries depict a unicorn hunt.

An abandoned stretch of highway, deteriorating next to the operational one.

House of vintage taxidermy and Steampunk sculptures in a quiet Pittsburgh neighborhood.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

A speakeasy takes on Chicago's drinking culture.

This naturally-sourced hot spring is now home to a clothing-optional resort.

A rare view of a preserved Victorian science museum.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

The first declared National Monument in the United States.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

Mysterious rocks that ring musically when struck.