This iconic water tower and failed bandstand is open for panoramic views once a year.

A Perpetually Under construction Park.

A whimsical sensor instrument for Minneapolitans to play on their walks to work.

A toweringly silly piece of modern art has been delighting locals since the 1980s.

Equal parts record-breaking temple to consumerism and bizarre fun park, it's more than you think it is...

Part of a worldwide art project, this mysterious semicircle of concrete shapes holds the pieces of a larger story.

Colorful collection of antique musical oddities.

You thought Santa Claus didn't exist, but it turns out you were wrong.

The farm where one of America's greatest leaders was raised is now a well-appointed landmark.

This open air cathedral invites all faiths to worship under the only roof big enough to fit them all: the sky.

One man's vision and a labor of love of many.

Symbolic attempt to overcome the issues of life.

A turn-of-the-century architectural marvel built on healing mineral springs and salt licks.

If astronomy had a ghost, it would look like this observatory.

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

This abandoned dream castle and its cemetery look out over the city that once inspired their creation.

The body of one of the world's most famous outlaws is covered in cement and iron to prevent it from being stolen.

This hidden stream beneath Indianapolis makes an appearance in the best-selling novel "Underground Airlines."

Once adorning a New York skyscraper, these reclaimed ruins now haunt an Indiana park.

The competition: breathe deeply as long as you can.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

Love, knishes, and best wishes from this legendary Lower East Side bakery.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.