Fortifications built for a Soviet invasion that never came now sit abandoned in a losing battle against nature.

One of the oldest structures in Helsinki is this burrow grave that dates back to the Bronze Age.

Hidden deep in a forest is this geological wonder carved by glaciers.

An incredibly durable timepiece glows beneath shoppers' feet.

This lonely rock has been turned into a character loved and feared by children.

This abandoned villa of makeshift buildings was once the home of dancer Elis Sinistö.

A replica of the home of a famous fictional troll family.

Tombstones buried in overgrown grass mark the deceased occupants of this abandoned graveyard.

Wars fought and wars won are remembered by these abandoned bunker ruins.

Crawling into this primordial cave may feel disconcertingly familiar.

Spend your honeymoon where the Devil had his wedding.

A secluded art gallery hidden within the cellars beneath Tallinn’s medieval monastery.

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

The world's largest model of our planetary system.

It was meant to help transport wounded soldiers to a secret underground hospital.

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

Stockholm's deepest subway station is also a stunning ecological wonder.

Outside a Viking museum sits a modern-day runestone made by a Swedish runemaster using traditional methods.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

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

This floating sculpture of ice is a poignant reminder of nature's power.

The design of this beautifully crafted building was inspired by Norwegian glaciers.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

One of the world's heaviest musical instruments towers within a popular urban park.