An ancient necropolis of magnificent tombs.

In the days before house numbers, these colorful signs held clues about various buildings' purposes.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

The attic of a four-century-old canal house hides a clandestine church.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

Inside this Icelandic greenhouse, geothermal energy keeps tomatoes warm and growing.

This hobbit-y little hot spring may be the oldest spring used by humans in all of Iceland.

Remains of the artificial harbours invented for the Allied invasion of Normandy can still be seen at sea.

This enormous "cloth of the conquest" depicts the Norman invasion of England in mind-blowing detail.

A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

This small museum nestled inside a souvenir shop is dedicated to Sweden's most well-known toy.

This gem from the industrial age helps visitors and residents alike traverse hilly Stockholm.

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

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

This Stockholm light tower can be controlled by anyone with a smartphone.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

An abstract monument to a symphonic composer.

A lovingly curated curio shop in which the taxidermy wear newspaper party hats, and peanut shells are spread across every surface.

This irregularly shaped sea fortress has defended not one but three different sovereign states.

An alien church provides much needed silence in the midst of a Finland shopping center.

A subterranean house of worship carved right out of the bedrock.

These temples are among the oldest free-standing stone buildings in the world.

The ruins of a megalithic monument sit right in the garden of a luxurious Maltese resort.

These lesser-known Maltese catacombs date back over 1,700 years.