Poland's oldest salt mine has nearly everything one needs to live underground forever.

Boats must transform into railroad cars to navigate this Polish canal.

A haunting deserted hotel is a favorite with artists and photographers.

A mysterious structure left behind on the Polish mountainside, sometimes called "Hitler's Stonehenge".

A peculiar family mausoleum built by a German nobleman captivated by the occult.

These massive moving sand dunes have swallowed an entire village and are still on the run.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

Museum dedicated to "the man who moved the Earth."

An abandoned Nazi explosives plant founded by the inventor of dynamite is now an underground museum.

Also known as "Robin Hood's tree," this tree became a famed location along Hadrian's Wall before it was cut down in an act of vandalism.

These precariously placed ruins harken back to a 13th-century castle.

This ancient castle has been abandoned since the Edwardian conquest of Wales.

Where, exactly, the great aviator completed her transatlantic flight has caused some trouble in Wales.

Go deep down into the earth to experience the world of Welsh coal miners.

The castle still holds traces of the abandoned Roman fort it was built atop.

The only medieval bridge in Britain with its defensive tower still in tact.

A tiny village in Wales claims the name of a noble medieval hound slain for a crime he didn't commit.

Fortifications built for a Soviet invasion that never came now sit abandoned in a losing battle against nature.

Did Gustav Eiffel design this enigmatic metal building?

Visit the WWII bunker where the British won the battle for the skies.

This vineyard was the site of the infamous Charge of the Light Brigade.

This 18th-century tower is locally iconic.

This abandoned nitrate town was repurposed as a dictator's prison.

Dedicated to the first German Chancellor, Otto von Bismarck, this aging edifice is the only one of its kind in the Americas.