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

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

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Every equinox this Maya pyramid puts on a spooky ancient light show.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

The glowing blue Nymphaeum of Emperor Tiberius.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Erotic art covers the walls of the largest ancient pleasure palace.

Ancient snack bar of the Roman Empire re-opened.

A world-class observatory in the California desert.

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

The largest earthwork effigy in the world.

Moonbows over Kentucky.

This replica of the Greek structure is in the heart of Nashville.

At 135 years old and counting, this historic print shop is heaven for poster nerds and music buffs.

A flamboyantly decorated bridge signals diversity and fellowship at the entry to Indianapolis' Broad Ripple Village.

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

The only freestanding table rock formation east of the Mississippi.

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

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

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

Symbolic attempt to overcome the issues of life.

One small town in the Pacific Northwest transformed itself into a Bavarian-themed tourist destination.

The highest point in Washington state is a volcano covered in glaciers.