The underground sanctuary of a mysterious ancient cult.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

See wolves, coyotes, and arctic foxes in a natural environment smack in the middle of New York State.

Located in Nairobi National Park, this animal orphanage is the oldest of its kind in Kenya.

Britain's only herd of free-ranging reindeer.

These "50 Fortresses" have been unearthed in the ancient oasis of Khwarezm.

Ancient barriers wrap around what was once an important stop along the Silk Road.

This "tower of death" has acted as an observatory, a religious hub, and an executioner's lair.

Once a bustling fishing port, this semi-ghost town is now more than 90 miles away from the shore.

The Avenue of Mausolea is a series of grand palatial tombs.

A long, winding trek rewards you with a gorge so captivating it inspired a painting in the Tate.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

This natural marble cave is one of only five national monuments in Oregon.

The trunks of 3,000 year-old trees lurk beneath the surface of this crystal clear lake in Oregon.

This great stone guardian of the forest is a relic from the land's volatile volcanic past.

Mountain known by the Tillamook Tribe as "the place of the supreme deity."

The first North American landing spot for James Cook on his third voyage of discovery in the Pacific.

The longest continuous lava tube in Oregon.

Formerly secret, precariously perched boulders.

This extinct shield volcano is the lightning rod of the Cascades.

The second largest waterfall by volume in the U.S., Willamette Falls is outdone only by Niagara in the amount of water that is pushed northward.

This Oregon farm is dedicated to teaching people the professional art of tree climbing.