Oriental bazaar in the heart of Sarajevo.

This historic cemetery was inaccessible for several years due to dozens of land mines.

The place where World War I began.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

A wunderkammer of gold and silver reliquaries and ancient saintly bones.

This picturesque medieval monastery guards a small trove of historic treasures.

This only museum in the world dedicated solely to mushrooms.

This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

This heart-shaped island looks substantially less lovely after a recent bulldozing project.

Croatia's "hairy stone" fortress is one of the most well preserved Istrian castles.

Legend has it fairies gathered at the site of this medieval castle.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

An 11th-century runestone decorates the halls of Terminal 2 of this Scandinavian travel hub.

Enormous ants wielding giant pine needles guard a Stockholm real estate company's office.

"Only the dead get off at Kymlinge."

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

This grisly exhibit houses skeletons and weapons from a devastating 14th-century clash.

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

It houses the remains of a 17th-century version of the Titanic.

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

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

An illuminated manuscript comprising the life's work of a lone monk, inexplicably decorated with a portrait of Satan himself.

Natural mummies hidden in the crypt of a medieval French church.

An architectural oddity of six stories, accessed by graceful ramps.