This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

A six-ton wedding present for the King of the Scots.

Protecting the dead from opportunistic body snatchers.

The tomb of one of Scotland's bloody historic villains is a magnet for bumbling desecrators.

A 18th century graveyard and its astonishing cortege of macabre iconography.

This series of Scottish caves has no clear purpose other than baffling historians.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

The final resting place of soldiers' loyal canine companions.

A book bound in the skin of an infamous criminal, along with countless other specimens.

360° views of the city plus five floors of optical illusions and hands-on science.

A sweet symbol marks the place where torturous executions were once carried out.

A monument hidden in the woods built in 1938 as a getaway for a Dutch museum curator.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Once the local rulers had gone these enchanting ruins housed common folk in an almost real life fairy tale.

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

A grassy pyramid named after a French battle.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

This impressive collection of rare books on ancient mysticism inspired author Dan Brown.

Museum preserving torture methods from the past.