Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

A popular swimming hole that hides one of America's most deadly diving spots.

An emerald-green grotto just a short trip from Austin.

A 24-hour vending machine restocked daily with homemade full-sized pecan pies.

Now abandoned, this East Austin school for the disabled began as the "State Colony for the Feeble-minded."

An entire subdivision was accidentally built on a flood plain, resulting in its eventual demolition—but the streets are still there.

This unique structure in suburban Austin is made up entirely of other people's castaways, and constantly changing.

This replica small town lets visitors take a stroll through the story of progress in the U.S. via thousands of Americana artifacts.

Empty, but not abandoned, this cavernous Brooklyn loading dock was once considered the largest individual building in the world.

Locals dubbed this abandoned abode the "gingerbread house" because of its odd architecture.

A late sculptor's last project was to turn this abandoned cement factory into a castle-themed amusement park.

An abandoned factory along the Mississippi coated by a giant mural.

An abandoned meat mecca now serves as an excellent locale for urban exploration.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

The overgrown remains of one of the premier auto-racing speedways in the Midwest—and also one of the most deadly.

An abandoned observatory in the middle of the Illinois prairie.

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

A key producer of charcoal iron in the early 1800s, the structure still stands today.

Settled by the Church of Jesus Christ of Latter-day Saints in 1859, this abandoned frontier town has appeared in several films.

A small flooded ghost town with a few scattered structures remaining.

One man's ambition created this psychedelic log home.

Built by prisoners of war, the largest small-scale model ever built includes eight miles of tiny streams that now sit abandoned.

Witnessing the might of this dessert-colored desert waterfall is a rare, powerful treat.

This historic national park is covered in the stunning ruins of red rock pueblos.