The mystery of the Putim Ossuary involves a tricorn hat.

An Austrian house of bones filled with hundreds of intricately painted skulls.

Structure built from the skulls of vanquished foes.

A church of bones, decorated with 40,000 human skeletons.

This 11th-century Greek monastery has renowned mosaics and relics of a brutal past.

A Victorian-style home known as the “Castle on the Hill.”

This house was the subject of an Edward Hopper painting, which in turn helped inspire the design of the Bates house in Alfred Hitchcock's 'Psycho.'

Not far from the more famous House of Juliet, visitors will find the supposed residence of her lover.

A line number in Amsterdam that will likely never be used again due to its tragic history.

A fantastical bed and breakfast with magically unique rooms.

The highest point in Belgium is a staircase to nowhere.

Abandoned since 1998, this train station has become an oasis for urban explorers.

This 1920s Dutch barge is now a floating bookstore.

A large collection of steam engines, organs, and fairground attractions.

In the quiet village of Fulmodestion, the ruins of a medieval church remain hidden among vines and foliage.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

This stately palace, first built in the 16th century, was converted into a prison in 1830.

Bacteria and algae give the salty water its bubblegum hue.

This Cold War–era fallout shelter was actually a storage facility for the nation's emergency currency.

A former ironworks that was the first UNESCO industrial site.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

The house where Harlequin was born.

A statue of the beloved storybook character stands in front of the building in which her creator was born.

Six paintings reminding you that death is integral part of everyday life.