Public works and national defense project meant to carve a canal all the way across the state of Florida.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

Quite simply the largest tree in the world (by volume).

One of the oldest living oak trees in the Southeast.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

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

The hallucinogenic center of the ancient world.

The ancient tomb acts as a calendar that keeps perfect time.

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

Pompeii's less famous neighbor is still revealing her secrets.

The oldest cemetery in New Orleans, resting peacefully for over 200 years now.

The first declared National Monument in the United States.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Famously misunderstood wonder of the ancient world

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

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

A hand-built folk art installation covered with messages of God's love.

Version of the French Riviera destroyed by the sea.

The ghostly remains of an accidental sea.

A fitting attraction for the corn capital of the world.

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