Treehouse motel and treehouse-building school.

This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

Rent out a glass igloo to watch the Northern Lights like you live in the future.

This giant boulder is pinched over a 1000-meter abyss by two mountains.

Rebuilt remains of a temple to Roman god Mithras.

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

The underground sanctuary of a mysterious ancient cult.

An Irish church where an 800-year-old mummy is reaching out of his coffin as if to shake hands.

The site of murders and Satanic cult gatherings.

A clear blue swimming hole with hidden caves, still unexplored.

This ancient village and its adjoining cemetery have a beautiful history of death and remembrance.

Extraordinary sculpture garden created by an eccentric English poet.

This sword isn't waiting for a king to pull it out. It was placed there by a saint.

This floating cinema brings new meaning to the phrase "going out" to the movies.

Hidden in an Italian forest is a completely homemade amusement park that has taken a lifetime to create.

"Respectful to the dead, safe and sanitary to the living, dedicated to the Genius of Memory..."

The glowing blue Nymphaeum of Emperor Tiberius.

This frequently-photographed waterfall takes only a short hike to visit.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

Remember that scene in the Matrix, when Neo is in the big white room with all the weapons flying by? Well, this is what it would look like if he had wanted trees instead of guns.

Skeletons dressed in extravagant 18th century royal costumes cavort in the aisles of this German basilica.

This expansive bridge in the Canadian wilderness was originally just built for friends.

An eccentric inventor's castle home with its own indoor weather system.

This 16th-century monastery has been turned into a surrealist architecture compound.