The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Original cabaret handbills, posters, and feline artwork are a purrfect highlight of the Museum of Montmartre.

The convergence of two currents makes this a surprisingly pleasant getaway in the Arctic Circle.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

Thousands of flowers create enchanting pink tunnels over the city streets.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

A walkable map of the world, made from soil and stone by one man.

This picturesque horseshoe weir was first built in the 1600s to prevent flooding in the town of Bath.

The world's only flying boat museum honors a small Irish village that sent 20th-century aviation to new heights.

A prized globe signed by Amelia Earhart and Charles Lindbergh sits in the Brooklyn office of the American Geographical Society.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

The state's only comprehensive museum dedicated to the mineral that defined its history and economy.

The oldest bibliophilia club in America, with exhibitions on historic books and graphic arts.

A Swiss board game museum housed inside a picture-perfect castle.

This gorgeous space is England's largest independent library outside of London.

A slightly creepy gallery of plaster cast models in the same museum as Michelangelo's David.

A collection of noses tucked inside an art museum reveals how times have changed.

This Brazilian town built by Freemasons is full of colonial Masonic architecture and symbolic imagery.

Something's watching you.

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

This delightful little museum is dedicated to only one thing: pasta.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.