The remains of the second-oldest zoo in Europe can be seen within these library gardens.

This small museum tucked within a subway station holds pieces from Madrid's past.

The earliest known map to show America, discovered by accident at a Paris bookshop.

The morbid items in this small and hidden museum are not for the weak stomached.

A lush indoor jungle fills this bustling Madrid transportation hub.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

A reproduction of the famous prehistoric cave paintings is hidden underground at the National Archaeological Museum.

A series of five defunct panopticon prisons in Cuba.

This mix of Islamic art, vintage vehicles, weaponry, architecture, and history is an ode to eclecticism. 

This unconventionally beautiful landscape possesses stunning scenery you won't easily forget.

Some of the ancient-looking huts among these strange rock formations aren't ancient at all, but built as part of a movie set.

These beautiful historic watchtowers were used for both scanning the desert for enemy invaders and observing the celestial world.

The building is a gigantic piece of art inspired by the shape of a desert rose.

A staggering number of rock carvings in an abandoned quarry.

A creepy, deserted mock Arabian village can be found in the middle of the Qatari desert.

The best-preserved example of a unique structure in Nubian architecture.

These pillars are one of the few remnants from the mysterious lost empire of Makuria.

Remains of an abandoned coral city.

A geological oddity topped with a 2,000-year-old pagan temple.

Called the "Armenian Stonehenge," this ring of menhirs pierced with holes may be a prehistoric astronomical observatory.

The observation point offers spectacular views of the ruins of an ancient Armenian capital.

This little medieval church hidden in the center of Yerevan was lost and rediscovered—twice.

Nestled in a peaceful valley, this Armenian monastery may have been saved from Mongols thanks to the eyes of God.