Hidden in plain sight, Sweden's official ordnance datum is now abandoned.

This pyramid in southern Sweden houses the remains of an eccentric nobleman, who spent his life doing whatever he felt like doing.

The world's only above water sand volcano, believed to once be the bathtub of a priest.

For a couple of months each year this Swedish city turns into a festive neon phantasmagoria.

A geological wonder that helped fuel myths of trolls and giants.

Said to be one of Sweden's most haunted places, this vicarage once even attracted a ghost-busting priest.

No one knows who's responsible for decorating this tunnel with stuffed animals, but the people love it enough to protest their removal.

Stockholm's tiniest statue is of a small boy looking at the Moon.

A colossal aqueduct from the second century B.C., deeply hidden in a gorge on the outskirts of Rome.

A floating underwater hotel, created by a Swedish artist.

A golden egg-shaped sauna in the Arctic tundra.

Now a hotel, this former bank was the site of a robbery that spawned a psychological phenomenon.

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

It houses the remains of a 17th-century version of the Titanic.

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

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

This cliff-face port is considered a masterpiece of mining engineering.

A former mining village that now operates as an open-air museum.