This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

The oldest of Venice's plague quarantine stations, designed to keep the medieval city safe from disease.

Originally a leper colony, the island is now an Armenian monastery that's home to an incredible manuscript library and eclectic museum.

This abandoned island off the Venetian coast has been a radical monastery, a political prison, and a secret Nazi base.

The plague quarantine island home to the alleged "Vampire of Venice."

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

Go inside to really appreciate this 500-year-old technological masterpiece.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

A 12th-century fortress containing some of Berlin's oldest buildings.

The most visited, and possibly most controversial, museum in Germany.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

This disappearing geyser has been attributed to witchcraft, but really it's all about rainfall.

This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

This modern arts center is built around a gem of late-Baroque architecture.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

This former Masonic lodge has been transformed into part museum, part bar, all awesome.

It is still illegal to "quarrel" at this unlikely urban oasis built on top of an electrical substation.

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

Remnants of a Victorian garden feature sitting in public woodland.

A historic house left in "dramatic still life."

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

This intricately carved and hilariously huge bed was such a famous symbol both Shakespeare and Byron used it in their writing.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.