Now nearly abandoned, Kaskaskia was once the capital of Illinois and one of the most important towns on the upper Mississippi.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

Beautiful stained glass depictions of the history of human flight fill this surprising chapel.

A portal into the bricked up canal that runs through the heart of Washington D.C.

One of the largest fleets of armored vehicles in the world, sitting out in the California desert.

Ohio's 19th-century communist micro-society.

More than 500 unique and specially designed cases collected by D.C.'s "Harmonica Case Man."

This Victorian marvel of engineering and artistic prowess is nicknamed the "Cathedral of Steam."

This abandoned fishing settlement may well be the greenest village in the world.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

A micro-communist utopia in Spain with no police, no mortgages and full employment.

Admire the art and then buy a raccoon skull cleaned by flesh-eating beetles.

A collaboration of art and ornithology mourns the calls of Sydney's lost birds.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

Hitler's bleak vision of relaxation still stands as a mostly abandoned 10,000-room resort complex.

A son's promise to his dying father in the form of a covered bridge filled with thousands of seashells.

This tree was extinct for a thousand years before sprouting again from a 2,000-year-old seed.

Colin Stokes "got a bit carried away" and built a castle that looks like something out of Tolkien.

A rapidly disappearing glacier filled with extinct grasshoppers, perfectly preserved in the ice.

A tiled, multi-level garden of survival in Lyon.

This handsome giant is said to mark the birthplace of the mythical woodsman and even had a cameo in a Stephen King novel.

The simple log cabin of a famed loner and naturalist stands preserved as a symbol of the ultimate DIY lifestyle.

The whole world in one water tank.

The longest navigable underground river in the United States is home to countless blind and albino animals.