Retirement home for giant obsolete machines.

Mysterious painted skulls in Moravia.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

A Spanish town built into the cliffs.

Humble beginnings for one of the world's most famous scientists.

"There's nothing there," and other lies the KGB told us.

Tombstones buried in overgrown grass mark the deceased occupants of this abandoned graveyard.

A decommissioned submarine base makes a great space for graffiti art.

An old hill fort covered in over 100,000 crosses is a symbol of Lithuanian nationalism and beliefs.

Since 1874, this macabre collection has developed into a museum devoted to Scotland Yard's mementos of dastardly deeds.

A hands-off space for graffiti artists to hone and display their skills.

Old batteries and frog skeletons reside in this lakeside monument to Alessandro Volta.

This Italian dam is covered in salt-hungry goats who manage to scale its almost vertical face.

A collection of objects supposedly singed by the hands of souls in purgatory.

Ever hear of the Milazzo Cage?

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

Venice's island of the dead.

Venice's "Island of the Mad."

Yugoslavia's biggest underground airport lies in ruins.

The only gulag ever to exist in socialist Yugoslavia.

Collection dedicated to funeral rites, equipment, and mourning rituals of the Viennese.

Museum dedicated to the terror regimes of Hungary.

Electrical curiosity museum housed in an old transformer station.

Once the home of a hermetic monk, this cave now houses a small church.