Possibly the oldest living thing in Europe, more likely a pagan survivor.

One of Scotland's most important modern structures, it just made the '100 Most Endangered Sites' list.

A small island abbey is the final resting place of many medieval Scottish monarchs, including the real Macbeth.

A pagan tradition of draping trees with rags eerily lives on.

The true age of this ancient stone circle is unknown, but its stunning vista isn't in question.

The ruins of this gorgeous clifftop castle look like something from a fantasy novel.

Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

This series of Scottish caves has no clear purpose other than baffling historians.

This castle was established by the 4th Duke of Montrose and is connected to the Buchanan Clan.

The last inhabitants of one of the U.K.'s most remote islands were evacuated in 1930.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

A strange rock with a sinister reputation lurks within the crimson waters of this Scottish glen.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

Large-scale contemporary artworks tower over fields and lurk in forests around a Jacobean manor house.

A forest park outside Tallinn full of architectural and artistic curiosities.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

A mesmerizing sculpture marks the site where the activist was arrested after evading capture for 17 months.

This spectacular bridge supported by two gigantic hands looks like something out of a fantasy universe.

Mysterious and ancient carved standing stones.

Visit this odd display of indigenous style in Argentine wine country.

A Swiss man built this airstrip for aliens because a UFO captain telepathically told him to.

This exceptional home was a 32-year labor of love by a man determined to build his wife the most beautiful stone house in the world.

Hopeless romantics will swoon over the sweet story behind this bright and colorful home.

This modern labyrinth lies in the shadow of a ruined medieval castle.