This artificial cave looks like something out of a fairytale.

A famous pilgrimage site that remains hidden in the midst of a city.

Breathtaking and huge 430 year old maps of Italy.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

A small but immensely extravagant palace built by the "Night King."

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

Tiny memorials honor individual victims of the Holocaust.

Germany's Glienicke Bridge has a shady history of clandestine meetings, espionage, and spycraft.

At one of Berlin’s oldest churches, visitors can place mosaic tiles to help restore a medieval mural.

From Iggy Pop to David Bowie to Nick Cave, this regal music studio has served some of the all time greats.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

Someone loved this song enough to carve all of its lyrics onto a tree trunk in a Berlin park.

This classic restaurant features a gorgeous mirror-clad room.

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

On high feast days, the entire blue-glass front of this modern church opens up to reveal the small wooden church inside.

This massive statue is the personification of Bavaria and the first colossal statue of the modern period composed of bronze.

This beautiful 19th-century temple stands atop the ruins of its predecessor.

King Ludwig I's collection of beautiful women.

Among the ostentatious rococo ornamentation of this church, an image of death cuts the life-thread.

The patron saint of spinsters grasps a container of dried blood.

Visit the birthplace of Charles Lutwidge Dodgson, better known as Lewis Carroll, poet and author of 'Alice's Adventures in Wonderland.'

Tombstones and enigmatic inscriptions hide within a vault beneath a popular London arts venue.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

Buried for centuries, this hidden cellar is all that remains of London's medieval Whitefriars Monastery.