A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

Home to items never before seen by the public.

This historic house museum that celebrates one of the world's most influential social reformers is also one of the most haunted locations in Chicago.

Huge masonic hall in Philadelphia with lavishly themed rooms.

A surreal statue honoring Prague's favorite literary son.

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

Macabre astrological automaton clock dating to the late 1400s.

The palatial McDonald's that inspired Wesley Willis.

This bronze sculpture on a former squash court marks the secret origins of the Atomic Age.

To find the "unicorns of the deep" you've got to go downstairs.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

Cemetery featuring rare glass-fronted columbarium.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

Five candy-colored villages on the Italian Riviera.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Inside this faux cave, visitors can learn how some of their favorite fantasy characters were created.

A New Zealand communications tower stands as the tallest structure in the Southern Hemisphere.

A verdant 17th-century-style garden hidden along Edinburgh’s Royal Mile.

This alley off Edinburgh's Royal Mile contains remnants of the city's seedier history.

Now home to a drinking establishment, this building has a macabre history.

This otherwise ordinary close on the Royal Mile constituted the end of the world for Edinburgh’s poorest residents.

This charming old building's loose connection with the Scottish Reformer is what saved it from demolition after it split apart.

The Scottish Reformation leader's grave was paved over and is now a parking lot.