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

Although rarely used, there is still a hidden room for the royal family at the Stockholm central station.

A temporary art piece to celebrate LGBTQ Pride is now a permanent part of Stockholm's traffic landscape.

Small Easter eggs are hidden in the ventilation holes of the city's newest trains.

An abstract representation of weather in Sweden.

This declassified Cold War bunker hosts a large collection of Swedish aircraft.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

This statue stands as a message against the ills of Apartheid.

Abstract marble carving for an 8.5-pound rock.

This poignant site pays tribute to one of Australia’s greatest actors.

A toxic lake near a volcanic caldera that is home to flamingos and other life.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

A beautiful but toxic fountain of mercury.

A mysterious castle built as a monument to lost love.

A thriving Black community was destroyed by an angry white mob at this site in 1923.

Wading through a small lagoon reveals a secret, wild stretch of pristine beach.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.