During the holidays, a vintage subway train whisks New Yorkers back in time.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

Constant erosion has created a surreal landscape of bleached and preserved fallen trees.

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

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.

12,000 sq. ft. museum tracing erotic art from antiquity to modern times.

This abandoned prison castle has become an imposing gallery of graffiti art.

Imagine playing a version of Legends of the Hidden Temple, but with a distinctly Southern Gothic flare.

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

Nonprofit art center that promotes outsider, intuitive, and self-taught art.

A Saint Nicholas-themed ghost town in the Mojave desert.

The site of murders and Satanic cult gatherings.

Great place to have a drink and a bite to eat in an atmosphere laden with New York's Bohemian past.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

Half of a waterfall goes into the river while the other half seems to disappear.

Treehouse motel and treehouse-building school.

An underground magnet for ever-changing street art.

The ghost town that ended up on Ebay.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

Houses are tucked between, on, and underneath giant boulders.

Thousands of well-dressed mummies below a monastery.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A curious collection of oddities including a lock of Alexander Hamilton's hair and Harry Houdini's ouija board.