Celebrating the Eucharist, the day is a legal holiday in many parts of Germany.

The fairy tale castle of the "fairy-tale king."

An eerie, derelict amusement park in Berlin.

The most visited, and possibly most controversial, museum in Germany.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

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

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

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

This "preacher's pulpit" once used for pagan ritual, is home to a new, and dangerous ritual.

Abbey built on the ruins of Roman catacombs.

Ancient paintings known as the "Sistine Chapel of Cave Art."

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

The fantastic architectural models of a French traveler.

A Gothic cathedral created from volcanic rocks.

One man's fifteen-year diversion lead to a garden of intriguing sculptures.

This beach runway is off limits during high tide.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

An ancient monastery, a locked room, and a mysterious book heist.

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

An intricate and amazing house built by architect Karl Junker.

Between Neo-Pagans and Neo-Nazis, these strange rock formations have a curious cult following and a very strange history.

Hundreds of prehistoric stones, arranged in perfect lines in a French field.

Northern Ireland's Brobdingnagian stepping stones.

Largest lake in Great Britain measured by surface area.