A former top secret military tunnel is now stuffed with snow and open year-round to skiers.

A historic scientific breakthrough that crosses nine borders.

The tallest lighthouse in the Nordic countries was also the site of a bloody World War II battle.

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

This abandoned office building is a lasting example of Soviet-era architecture.

The widest natural waterfall in Estonia is a sight to see in all seasons.

This old Estonian mine has been kept like a sprawling time capsule of the local shale industry.

This peculiar border irregularity is the only way to legally enter Russia without a visa.

Relics from an era long gone, sit idle outside this Estonian museum.

Legend says lovers who hold hands while venturing along this stone jetty and kiss at the end will remain together forever.

A decommissioned submarine base makes a great space for graffiti art.

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

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

This disappearing geyser has been attributed to witchcraft, but really it's all about rainfall.

Mysterious craters may have been home to an ancient cult.

The 3.8 billion-year-old rock proves that tectonic plates may have been shifting longer than we thought.

These eight mummies are the best-preserved human remains ever discovered in North America.

The world's northernmost flowers cling tenuously to life on desolate Kaffeklubben Island.

A surprisingly beautiful abandoned World War II military base in East Greenland.

A century-old church is now a space museum with a treasure trove of Soviet space items.

A subterranean Holocaust refuge within one of the world's longest cave systems.

One of the most extreme deserts in the world, these snow-free valleys harbor life, despite the hostile environment.

Antarctica's bustling metropolis, originally established by Richard E. Byrd.

This abandoned Antarctic research station is a Soviet ghost frozen in time.