The last physical evidence of the Lewis and Clark trail is one of their autographs etched into this giant rock.

An architect's childhood fantasy treehouse made real.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

Famously misunderstood wonder of the ancient world

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

One of Ireland's most infamous prisons for rebels including men, women and children.

Walk in the footsteps of the gods and straddle two tectonic plates.

Medicinal spa created with the discharge from a geothermal energy plant.

A six-ton wedding present for the King of the Scots.

An impromptu shrine appeared shortly after beloved "Torchwood" character Ianto Jones was killed off the show.

Recently restored menagerie of Victorian-era beasts.

This Welsh village gave itself a ridiculous name in a publicity stunt a century ahead of its time.

The highest peak in Wales is said to be the final resting place of a giant killed by King Arthur.

A harem-inspired Moorish fantasy design in a Victorian-era Welsh castle.

Europe's largest prehistoric mound – burial site of a legendary king?

The largest stone circle in the world has ended up bringing up more questions than it has answered.

The oldest inn in England served brew to the crusaders.

The granddaddy of English geoglyphs dates back to the late Bronze Age.

An interesting decoration on this historic site, this weathervane comes with as many legends as it does questions.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

This monument on Breed's Hill proves that one of the most famous battles of the Revolutionary War is misnamed.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.