Radioactivity still cause for concern at this urban explorer's paradise.

A pier that used to act as a busy ferry dock is now a decaying favorite of local fisherman and urban artists.

An archive of nearly every day of Buckminster Fuller's life.

One of the largest free-standing structures ever built, this dirigible hangar is now simply a giant skeleton.

The largest permanent Monopoly board makes one of the longest games even bigger.

The "Fun Spot of the Desert" is now a haunting ruin, and a reminder that putting a water park in a desert is a bad idea.

A psychedelic labyrinth on the San Francisco bay.

Join the circus for a few lessons to learn clowning, acrobatics, and Chinese contortion.

A museum befitting the city responsible for supplying the majority of the world's LSD.

The thousands of shades on display — some toxic, others impossibly rare — are a library of more than just color.

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

This upscale streetwear store is hidden behind a fake Snapple machine in the back of a deli.

This art center is way beyond your average pumpkin-carving operation.

These expertly crafted, scientifically accurate glass sea creatures were once an international phenomenon.

Pluto is still considered a planet in Ithaca, New York.

This collection started by a Cornell professor once held more than 600 human brain specimens, including the one that belonged to its founder.

The library of every book lover's dreams.

In upstate New York, gorgeous waterfalls and a watermill are slowly being reclaimed by nature.

A UFO scrapyard in the California desert.

The unbelievably opulent home built for an infamous newspaperman.

Cambria's most unique B&B features creative surroundings and fantastic food.

Machinery left over from California's once thriving mercury industry now attracts artists and explorers.

The ruins of the castle that chemicals built.

This stretch of beach along California's central coast is a busy highway for the largest seal in the northern hemisphere.