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

Less a museum than a bizarre fantasy world created by artists and engineers.

The king of U.S. high points towers over every other peak on the continent.

Famous for its bio-luminescent inhabitants, known as "dismalites."

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

The remains of an idyllic small town built for the film 'Big Fish' still stand around a rundown main street.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

Rippling sand dunes frozen in the Arizona rock.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

Beating out all other concrete competitors, this massive garden feature's pointy hat has earned it a world record.

A whimsical village of unique treehouses resides in a Washington forest.

A wall of chewing gum moonlights as collective art.

Natural time capsule containing an alien ecosystem.

This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

This community on a small Venetian island has taken to painting their houses in bright neon hues.

Iceland's largest lagoon is home to stunning multi-colored icebergs.

Walk 2,300 feet above the ground on the "Troll's Tongue."

The world's longest known cave system.

Where beautiful signs live on forever.

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.