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

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

Try not to get slimed in Tribeca.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

This massive tea kettle was once a promotional stunt for the Oriental Teashop.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

A mysterious stone embedded at the base of a historic Boston building.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

The house that took a plunge into the facade of a museum.

Monument to a suicide protesting the Soviet invasion.

Increasingly decayed figures stand as a powerful reminder of the human costs of Czech Communism.

This Prague museum collects brutalist relics and memories from the country's former Soviet rule.

A mocking tribute to the past and modern leadership of Prague.

The world's largest maze is a nature park with nearly 200 decision points.

A curious collection of locks and keys.

A museum which takes visitors to the côté obscure of Paris.

The personal library of the founder of modern neurology is open to visitors.

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

Abandoned railway line circling the city of Paris.

The curious underground history of keeping Paris clean.

Inside a former cabaret, seven floors of erotic art.

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