An unfinished tomb carved into a giant boulder in the Arabian Desert.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

Once described as the "Eagle's Nest," this ruined ancient city rests on a remote mountaintop.

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

What was once the second largest steel mill in the US is now a sprawling complex of modern ruins.

This crumbling Portuguese ruin overlooks the populace it once ruled.

A small metropolis of Pueblo cave dwellings have been carved right into the hillside of this national monument.

These gutted monastery ruins still stand proudly in the middle of the Italian countryside.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

A magnificent, iconic stone tower in the Scottish Highlands.

A full-size replica of this well-preserved temple lets you take a walk through the Mayan age.

This haunting ghost ship stands beached in the waters off the coast of the Falkland Islands.

An FDR-era tuberculosis sanatorium has stood abandoned in the suburbs of the U.S. capital for over 30 years.

What remains of the summer palace of King Kamehameha III.

This historic national park is covered in the stunning ruins of red rock pueblos.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

Hidden just under the waters around this Turkish island are the ruins of a once great city.

This once-palatial plantation may have been the site where a draft of the Declaration of Independence was written.

A Franco-era dam flooded (almost) everyone out of this centuries-old Aragonese town.

The ruins of this old church are slowing sinking into the sand.

Stroll through a wonderland of stupendous moss-covered trees.

Who needs fancy modern water slides when this giant North Carolina rock works just as well?

Once an ambitious nature spa, these forest ruins now provide a serene monument to failure.

When this test site was abandoned, they didn't even bother to take the rocket with them.