A fantastic castle rumored to be the birthplace of King Arthur.

This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.

The largest hewn stone in history.

The largest Neolithic ruins in the world hide a notably clean prehistoric metropolis.

See the computer’s history revealed over the course of 20,000 years.

Spain's stunning solar energy plant.

America's only nuclear missile silo open to the public.

"World machine" built by an untrained Austrian farmer.

Charles Babbage's proto-computer, painstakingly brought to life.

A clock designed to run with perfect accuracy for 10,000 years.

Light still pours into the ruins of this ancient Islamic observatory.

A seemingly simple canyon that was the backdrop to a number of famous movies.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

Stone Age solar temple is aligned with the sun on each equinox and solstice.

The real life Hobbiton, this sheep farm has been forever transformed since being built for The Hobbit film series.

Buildings from the fictional planet of Tatooine still litter the Tunisian desert.

Abandoned medieval hill town.

Large Hadron Collider and the Birthplace of World Wide Web.

The original film set of Luke Skywalker's Tatooine home from the 'Star Wars' trilogy.

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

This hunter-gatherer architecture is believed to be the oldest religious complex known.

A geological bull's-eye visible from outer space.

A museum filled with tiny, adorable versions of the mighty Royal Danish Navy.

This Croatian island is for sale but no one is buying due to the dozens of accused Nazi sympathizers who were massacred there after WWII.