In paradise, feral pigs have claimed an island all to themselves.

An underground city of salt.

The largest underground church in Europe.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

The mortal remains of an estimated 70,000 people lie in the basement of a monastery in Lima, Peru.

A series of five defunct panopticon prisons in Cuba.

Cliffs full of fossils at the portal to England's Jurassic Coast.

The world's most remote permanent settlement on an active volcano.

Snow-capped peaks, colorful waterfalls and stunning vistas on the edge of the Himalayas.

Where the high court feasted, frolicked, and high courtesans put their royal lovers' diamonds to the test.

A rocky Irish outcropping with a history of wealth, conflict, and ruin.

Catacombs turned marketplace.

A massive sea stack famous for its appearance in The Goonies.

The smallest country in the world.

Beneath the city of Lourdes, France is a massive, concrete church.