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

A centuries-old iron mine is now a paradise for explorers, divers, and spelunkers.

Despite the groans of archaeologists, this astounding groups of Bronze Age petroglyphs have been painted red for tourists.

This giant boulder is pinched over a 1000-meter abyss by two mountains.

Believed to be the country's tallest waterfall, the Njupeskär is actually much smaller.

A stunning silver lining to global warming's gloomy cloud.

Walk 2,300 feet above the ground on the "Troll's Tongue."

Norway's chilly all ice-instrument festival.

An unusual sand beach in the middle of a forest.

"In the Dark" Restaurant in Paris offers dinner in complete darkness.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

This massive library holds what was once the largest book collection in the world.

France's national museum of scientific and industrial instruments.

One of the oldest masonic museums in Paris.

A subterranean shelter remains intact under a busy Paris railway station.

The mummified heart of Louis XVII, the lost dauphin of the French Revolution.

The only remaining collection of flayed figures made by French "madman" Honoré Fragonard.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

The walls of these four caverns are filled with art that dates back to the earliest human presence in Europe.

A spectacular walk on the flank of a gorge.

The spectacular geological formations make it one of the most impressive caves in Europe.

A prehistoric cave in Spain contains paintings dating back to the Ice Age.

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

Devastated landscape used for hundreds of years by the Romans as their primary mining site.