This freshwater spring fills with 10,000 gallons of water per minute.

This long unused shot tower on the Mississippi remains a point of pride for a small city in Iowa.

The largest self-built castle in the U.S., six decades in the making.

The world's largest woodcarving collection includes dozens of Bible scenes and a wooden bestiary, all carved by one man.

In 1953, a group of Wisconsin high school students helped build a hospital by collecting over a million pennies.

Meet the "Green Monster" of Monico, Wisconsin.

A fairytale art house in the middle of Wisconsin.

An oddly poignant roadside attraction celebrating American folklore.

The menacing creature had a tremendous influence on the local culture before being exposed as a hoax.

A museum devoted to the victims and the survivors of the most catastrophic fire in American history.

Fourteen curious and controversial white bunnies sit in a circle near Newport Beach City Hall.

The famed architect designed this Minnesota gas station of the future with a lookout tower.

At this Denver landmark, the meals are compulsory, the sopapillas are complimentary, and the insanity is everywhere.

America's most famous piece of self-built architecture.

Restaurant in Northern Wisconsin comes with a unique feature: a grassy roof covered in living goats.

A house and yard adorned with bizarre concrete sculptures in a Milwaukee suburb.

A bedazzled house and crown "jewel" of outsider artist Loy Allen Bowlin.

Whimsical sculptures dot a woodland path surrounding their creator's old summer cottage.

A museum celebrating the self-taught artist-environment builder.

A sculpture made of 10 Cadillacs as a monument to the “Golden Age” of the American automobile.

Inside this museum resides a boot fit for a giant.

Also known as the Temple of Poseidon, this is one of the best-preserved Greek temples in the world.

Unscathed for almost 2,000 years, the best preserved Roman triumphal arch is in a small southern Italian city.

People have been living in the cave houses on this Italian hillside since the Neolithic era.