The perfectly preserved underground rooms where Churchill plotted the war against Germany.

A hands-off space for graffiti artists to hone and display their skills.

An unusual round church in London with a Templar past.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

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

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

The legend associated with these ruins understates the splendor of the mansion that once stood here.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

Charles Dickens was not a fan of the ghastly wall dressings in this 6th century church.

The underground sanctuary of a mysterious ancient cult.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

Gods clash with machines in a power plant regenerated as a museum.

A hospital where antique dolls are given new life.

A 16th-century horror show built in a lovely Italian garden.

A majestic lion statue guards this Parisian botanical garden, and feeds on an unsettling item.

Where the high court feasted, frolicked, and high courtesans put their royal lovers' diamonds to the test.

A curious collection of locks and keys.

Noirish green neon marks the location of one of the oldest private detective agencies in France.

Dolls of all shapes and sizes display the eras of femininity in this spooky and beautiful collection.

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

Painstakingly built dioramas sit unnoticed in a Boston office building.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.