A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

A museum that chronicles the history of the Nuremberg Trials for Nazi war criminals in the building where the trials were once held.

A copy of the Statue of Liberty greets visitors to the birthplace of Auguste Bartholdi.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

Historic medieval fortified city in southwest France.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

Devastated landscape used for hundreds of years by the Romans as their primary mining site.

An Antoni Gaudí masterpiece in Astorga.

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

A road that winds through this natural cave is the only way to access the small, appropriately-named village of Cuevas.

Giant topiary dog once played a role in a terrorist bomb plot.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

Bordered by forest on three sides and the ocean on the other, the Great Dune of Pilat is the highest sand dune in Europe.