An ancient and majestic fortress that played an integral role in Portugal's road to independence.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Where commuters walk through remnants of an ancient Greek necropolis.

An ancient octagonal weather station named for the eight Greek gods of wind.

The hallucinogenic center of the ancient world.

Monasteries on rock pillars, once accessible only by frayed ropes.

The notorious "Hanoi Hilton" where Vietnamese colonial subjects and later American POWs, including John McCain, were imprisoned.

Home of the unusual art of water puppetry, one of Vietnam's oldest curiosities.

This Cambodian riverbed is covered in ancient Hindu carvings both above and below the waters.

A battle between nature and architecture in the Cambodian jungle.

A steaming, boiling hellscape sources Hokkaido's thermal baths.

The statue's head is one of the few fragments of the original Urakami Cathedral to survive the atomic bomb.

A plaque marks the site directly below the mid-air detonation of the atomic bomb over Hiroshima.

Peace Park and the Atomic Bomb Dome.

Japanese national treasure originally built in 593 CE.

World's first "penitentiary," meant to be humane, drove men insane.