This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

This impressive chasm is one of the longest natural underground cavities in the world.

This medieval village clings to a cliff in southwestern France.

Ancient paintings known as the "Sistine Chapel of Cave Art."

Every year, a sparkling cave is sculpted in the icy heart of a glacier.

A fortified palace in the shape of a ship on the Thiou river.

Where the legendary wizard sleeps for eternity, according to Arthurian lore.

A medieval house adorned with enigmatic carvings, including one of a man displaying his masculine attributes.

Hundreds of prehistoric stones, arranged in perfect lines in a French field.

The haunting concrete remains of a Nazi pebble crusher can still be found in this small French commune.

The Jardin d'Étretat is populated by over-sized raindrop sculptures that make funny faces at visitors.

In 1927, a biplane disappeared while attempting to complete the first non-stop transatlantic flight between Paris and New York City. This memorial stands at the last place it was seen.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

This statue honors the thousands of Allied avians that served and died for France during World War I.

Tables of secondhand books fill the inner courtyard of this 17th-century stock exchange.

An astounding collection of taxidermy, fossils, skeletons, and even a few strange live beasts.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.

In the heart of Tirana, this underground nuclear bunker has been transformed into a museum.