The perfectly named cave drop is the deepest in the continental United States, almost matching the height of Seattle’s Space Needle.

Crumbling ruins mark the site of a couple's grisly murder in the woods.

Live long and prosper in Tennessee.

A miniature city built by a single hunchbacked monk.

More than five miles of underground passageways.

Mysterious library of an infamous financier and spiritual seeker.

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

Bananas are often left for the first monkey America ever recovered alive after being launched into space.