These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

These former Cold War launch sites have been preserved for tourists to see where the button might have been pushed.

A museum within a museum, devoted to history's most questionable medical devices.

These curious caverns have been home to mushrooms, gangsters, and disco.

The Midwest's reigning king of surplus stores is full of nothing you need and everything you want.

This taxidermic smorgasbord was co-created by an artist poached from the Museum of Natural History.

This bright yellow building is packed with sweet treats from all around the world, from chocolate-covered crickets to whoopie pies.

Beyond being incredibly fun, not much can be said about the Hole with certitude.

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

The seamy, underground secrets of Portland's criminal past.

This extravagant Art Nouveau rest stop features a million-dollar view of the Columbia River.

An extraordinary mixture of natural beauty and man-made phenomena.

A stunning landscape of bunkers that once stored chemical weapons.

Nuclear reactor created the plutonium used on Nagasaki.

A 1940s nuclear reactor built to produce plutonium for the Manhattan Project.

A diorama lover's dream world.

It was once used as a classroom to teach mining skills to local high school students.

This oddity shop contains everything from antique tools to a human skeleton.

This trail leads to a mine that was used as a sanctuary during the Great Fire of 1910.

A mining town, now abandoned, was built in a canyon so narrow that the railroad ran right through the hotel lobby.

This angular Dwarven tunnel cuts through a mountainside in Glacier National Park.

With over 340,000 artifacts and counting, there is something for everyone, often called the "Smithsonian of the West."

The last physical evidence of the Lewis and Clark trail is one of their autographs etched into this giant rock.

The deserted railroad town had a last gasp as a ghost town attraction before being abandoned for good.