A morbid secret lies hidden within the beautiful walls of the Boston Athenaeum.

A beautiful Victorian-era cemetery, complete with a miniature village.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

A dark, dank room in subterranean Manhattan was the site of a ghastly murder.

Relics given to a Manhattan church to avoid seizure by the Italian government.

An otherworldly, fossil-rich cobble beach holds Viking graves, cairns, and other remains.

Located in an old church, this brewery produces a different kind of holy water.

A simple stone remembers one of the most menacing horses in the Swedish military.

A plaque marks the house in Stockholm where the French philosopher René Descartes lived up until his death.

Hidden in plain sight, Sweden's official ordnance datum is now abandoned.

Every Tuesday, students let off steam by screaming into the night air.

Stockholm's narrowest alley is barely over two feet wide.

The discovery of an old wall led to the creation of this fascinating museum about the city in the Middle Ages.

A golden plaque marks the site of the mysterious unsolved assassination of the former Swedish prime minister.

This giant crucifix is like U2's Joshua Tree for Swedish death metal fans.

The scars of a remarkably organized public protest to save 13 elm trees are still visible in this Stockholm park.

Although rarely used, there is still a hidden room for the royal family at the Stockholm central station.

"Only the dead get off at Kymlinge."

The single richest source of elemental discoveries in the world.

Dine on food tied to Viking history and legend at this subterranean Stockholm spot.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

This homeless brass fox tugs at your heartstrings from the foot of a Stockholm bridge.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.