Mine shafts and hard pastries await visitors at this massive mountain of salt.

Human-made caves excavated to hide a secret society of wealthy pagans.

This massive library holds what was once the largest book collection in the world.

A huge wooden clock that is so beautiful its creator was forcibly blinded.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

This star-shaped military outpost is now simply trying to protect itself from neglect.

Striking occult iconography on a medieval German church.

These quaint French houses dangle precariously over a precipice.

Ample proof that watery ends make for well-preserved, millenia-old mummies.

The works of poetry's biggest names grace the walls of the city of Leiden, all carefully painted by hand.

France's national museum of scientific and industrial instruments.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

One woman's decades-long obsession with the "La Fée Verte."

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

The industrial monstrosity known as Bagger 258 is a colossal mining machine built in the DDR - but now left for dead in a German field.

Besieged by war, this castle ruin has crumbled into a peaceful picnic spot.

Monsters and miniatures are held in equal esteem at this wondrous museum.

An impressive monument to Poland's independence.

A 200-year-old prison that now houses a peculiar crime museum.

A preserved dragon's rib that remembers the legend of the founding of the city of Atessa.

Modern art commemorates one of the first military actions of World War II.

An extraordinary library and archive dedicated to the history of the Arctic and Antarctic poles.

Art and armour fill every inch of this rich kid's Italian villa.

This famous city eluded concrete detection until the early 2000's.