Long abandoned underground complex to keep royals safe from a nuclear war that never came.

There are plenty of wonderful panoramic vistas in Edinburgh, but not many are hidden smack in the middle of the Old Town.

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

Accessible only at low tide, the deserted island is dotted with World War II ruins.

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

Tiny effigies of the victims of Edinburgh's famous Anatomy Murders.

The fountain marks the area where hundreds of accused witches were burned at the stake.

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

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

The abandoned tuberculosis sanatorium is said to be one of the most haunted places in Canada.

Home of Jake the Alligator Man, the mummified remains of a cigar smoking, cross-dressing celebrity of the Northwestern coast.

Collection of antique taxidermy and natural specimens, near one of Paris's oldest flea markets.

A 400-year-old church covered floor to ceiling in ex-voto offerings from the faithful.

The remaining relics of the patroness of Paris lie in a chapel under a striking double spiral staircase.

An off-the-beaten-path boutique stuffed with an eclectic collection of upcycled goods.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

In this Parisian garden's grotesque former life as a zoo it fed exotic animals to the bourgeois and put humans on exhibit.

This banal Parisian entranceway is not what it seems.

This little-known relic crypt holds stolen parts of a Roman Empress.

The recovered bones of martyrs slaughtered during The Terror are on display in this church crypt.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

A popular shrine where the Blessed Virgin allegedly appeared in 1830, displaying a holy armchair and two incorruptible remains of Lady Saints.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.