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

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

An ancient fortified mound raised over the millennia from settlements built one on top of the other.

The largest catacomb system in the world.

Featured in one of the most iconic scenes in cinema history.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Quite possibly the oldest love poem known to humankind.

Inside the Wayne County airport is an amazing collection of lights and sounds.

Disused seaplane hangar gets a second life as the jaw-dropping home of Estonia's museum of maritime history.

The oldest continuously operating pharmacy in Europe.

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

Walk along the medieval fortifications that have been protecting Tallinn since the 14th century.

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

Sweden's "good old days" painstakingly re-created in a model village.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

This chimerical bridge/tunnel appears to dead end right into the sea.

Swedish skyscraper with a 90° twist.

This collection of 80 polarizing foods aims to challenge your subjective notions of repulsion.

Liechtenstein's royal family calls this medieval alpine castle home.

A forgotten remnant of the Soviet Union, Transnistria is an unrecognized country hidden behind a heavily militarized border between Moldova and Ukraine.

This abandoned Soviet circus is slowly being restored to its Communist-era glory.

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

No one knows who's responsible for decorating this tunnel with stuffed animals, but the people love it enough to protest their removal.