A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

Cat art as far as the eye can see.

This bright yellow relic is the final survivor of a short burst of seashell-shaped petrol pumps.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

Part modern art project, part traditional chapel, this see-through church is only substantial from the right angle.

Open-air museum with an elaborate sculpture garden, stretching for over 70,000 square-meters.

A park full of outsider art, created by college students studying outsider art.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

Gigantic unfinished stupa and the world's 2nd largest bell.

Island ghost town detailing Flagler's folly in building the Overseas Railroad.

A layered tribute to the work of mosaicist Isaiah Zagar.

In the early 1800s, surgery was also a show.

One of the world's largest model railroads is a mind-boggling achievement.