The headless bodies of more than 1,300 guillotined victims of the Reign of Terror are buried here in mass graves.

Down a pint of ale where the Bishop of Ely's servants slept in 1546.

The largest clown school in Britain offering accredited degrees.

A building that survived WWII, possibly on the virtue of its name alone.

Tucked away behind the mansions of Mayfair, this picturesque garden is a hidden London treasure with a spooky past.

The largest of London's subterranean rivers and once a mad, bad center of London life.

This 1920s Dutch barge is now a floating bookstore.

Vienna's underworld of tunnels and subterranean rivers made an iconic appearance in a 1949 Orson Welles film.

Handsomely crafted representations of our round planet.

Dine amidst exotic plants at this former royal greenhouse.

The final resting place for the remains of 143 Habsburg royalty.

Macabre museum devoted to historical Viennese murders.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

A two-way chairlift system between Zugliget and the highest point in the city.

A Hungarian pharmacy museum with a box full of mummy powder.

A museum in the childhood house of a medical pioneer.

An artificial crater field that trained astronauts for lunar exploration.

A mass grave for victims of an airline disaster that led to much-needed safety improvements for commercial flights.

Back in 1952, you could get a mushroom cloud chaser with your atomic cocktail.

An Englishman loses his scalp to a Cheyenne warrior and lives to donate it to a library.

A speakeasy takes on Chicago's drinking culture.

This hidden labyrinth offers walkers some brief peace of mind.

Run by a eugenics advocate, this aging institution conducted secret radiation experiments sponsored by Quaker Oats.