Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

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

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

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

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

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

Notorious artist squat renovated into legal studios.

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.

A special shop catering to the needs of things that go bump in the night, and also helps kids become writers.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

Hidden beneath the streets of London is a secret subway that only carried mail.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

A faded sign from the 1920s remembers Baltimore's resistance toward banning alcohol.

Ship skeletons haunt Baltimore's waterways.

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.

A 200-year-old bar with a cheeky name claims to have served Edgar Allan Poe his final drink.

This free, take-a-book shop seems like a trick but isn't.

The site where Poe "in great distress, and ... in need of immediate assistance" likely died.