The two abandoned overpasses are among the largest bridges in Poland.

A small granite monument marks where the borders of three countries meet.

An engineering marvel at the time of its construction, this cross-border waterway sought to connect the Black Sea to the Baltic.

Boats must transform into railroad cars to navigate this Polish canal.

This 13th century Gothic brick castle is the largest in the world by surface area.

A southern Swedish island is home to the last ERSTA artillery battery, meant to protect the shoreline during the Cold War.

The oldest Swedish built lighthouse still guides ships through the archipelago.

The fastest way to send a message before electricity was invented.

This museum of Viking vessels allows visitors to take a replica out for a spin.

This 2,000-year-old stone maze is one of the oldest in the country, but its purpose is still a mystery.

This patch of land is home to Sweden's largest burial mound, allegedly belonging to a mythical king.

Unfortunately, you can no longer spend a night in this single-person treetop hotel.

This runestone once destroyed by an explosion has been painstakingly reassembled to save its history.

The final resting place of a young stagecoach robber who refused mercy.

A flock of peculiar-colored sheep graze in this small Swedish town.

This Swedish sculpture park is a unique combination of ancient ruins and modern art.

This underground car park moonlights as a permanent art exhibition.

A semi-sterile mutant birch that became Sweden's national tree.

A reproduction of a mysteriously preserved body found in the 18th-century and put on display for years before burial.

A centuries-old copper mine that once provided two thirds of the world's copper supply.

This Dalecarlian horse is about the size of a pinhead.

A medieval church that contains murals from famed artist Albertus Pictor.

This Viking Age memorial contains the oldest known image of a Täby resident.

A Swedish phone box converted into an informal village library.