This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

The oldest stone house in Paris was built by its most famous alchemist.

Notorious artist squat renovated into legal studios.

France's most famous cemetery, with some of its most curious tombs.

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.

The final resting place of soldiers' loyal canine companions.

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

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

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

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

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

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

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

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

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

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

A British plaque explains that a house was built using the spoils of the first international golf bet.

Every birth, death, and marriage is recorded in these color-coded leather-bound books.

This small museum in a 17th-century building honors three iconic Scottish writers.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.