A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

A terrific purveyor of natural history objects and curios.

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

The once great capital of Egypt now crumbles forward as evocative ruins.

Known as the Sistine Chapel of Egypt, this tomb houses some of the most well-preserved paintings in Egypt.

A massive work of modern art that appears to be a crop circle in the middle of the desert.

An alien landscape of chalk-rock in the Egyptian desert.

An endless sea of white conical domes.

Perched above the bustling town of Kerak is a sprawling, ruinous castle that has witnessed nearly a millennia of Levantine history.

Known as the "Valley of the Moon," this Jordanian wadi is one of the most amazing desertscapes on Earth.

The district's only illusionarium supports free writing programs for local students with every purchase.

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

People escaping slavery may have hidden inside a corpse vault.

A wondrous old library overlooking the nation's capital.

This peculiar museum offers hands-on interaction with seemingly intangible principles of mathematics.

Four-story slides send people whizzing through the math department at this Munich university.

From Ancient Rome to WWII, Neupfarrplatz has over 2,000 years of history underneath its main square.

An abandoned swimming pool decays on the outskirts of Berlin.

No need to strap in for a "ride" on this walkable roller coaster.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.