A preserved Nazi labor camp now has a Holocaust museum on site and memorials to the thousands that died while imprisoned at the camp.

From Nazi chemicals to the CIA, this architectural marvel has played a fascinating role in German history.

The fairy tale castle of the "fairy-tale king."

World's first "penitentiary," meant to be humane, drove men insane.

World's largest collection of serial killer artwork and other macabre exhibits.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

The castle still holds traces of the abandoned Roman fort it was built atop.

Recently restored menagerie of Victorian-era beasts.

High Victorian fantasy created a fairytale castle out of a ruined fortress in Wales.

This crumbling 14th century chapel became so unstable the roofing apparently collapsed during a wedding ceremony, narrowly missing the curate's head.

This ancient Bedfordshire church was abandoned when the village's population slowly began migrating to new towns.

A reportedly haunted 14th century church is curiously facing the “wrong direction.”

An exquisite Baroque church in Vienna's old town.

This cubist Vienna church building looks like some sort of alien stonehenge.

The resting place for anonymous victims of the Danube's dark waters.

Located right outside of Vienna, visitors can take in expansive views of an ethereal forest.

The beautiful baroque library of the Hapsburg empire.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

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

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

Northern Ireland's Brobdingnagian stepping stones.

A 30-acre garden inspired by the principles of modern physics.