The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

This tiny island featuring 9th-century Viking ruins is only accessible at low tide.

This king penguin is a knighted brigadier of the Norwegian Army.

A statue in the heart of Edinburgh honors a bear that served in the Polish military during World War II.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.

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

Famously misunderstood wonder of the ancient world

Rebuilt remains of a temple to Roman god Mithras.

The sign at the garden gate reads: "These Plants Can Kill."

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

A fascinating insight into daily life in the Eastern Bloc.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

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

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

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

After being destroyed by IRA sympathizers, the ruins of this stately Irish manor have sat vacant for decades.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

A stunning Victorian abbey and walled garden on a lakefront.

One of the most popular megalithic sites in Ireland stands as a humbler version of Stonehenge.