This haunted hotel built on natural springs once served as a hospital for a quack doctor promising a cure for cancer.

In the 9th-century this small spring-fed well became the location of daily mealtime miracles for one Saxon monk.

A KFC honors an eighth-century Chinese poet with holograms and verse.

A replica of a 7th-century church hides in plain sight in the middle of the concrete jungle.

This innocent-looking townhome is actually a subway exit.

A semi-scholarly approach to sex.

A limestone sculpture of a praying man resides over the site where 23 Chinese cockle pickers died.

This popular square's history as the former site of a church is right beneath your feet.

Artistic tombs, monuments, and a beautiful "Hall of Fame" lurk inside this cemetery.

A monument to the two U.S. officers killed by North Korean troops while trying to trim a poplar tree.

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

A popular oddity on display in a stately building, offering a symbolic commentary.

The extensive relics of an ancient Roman and Phoenician fish processing plant hide in a town park.

Living towers made of people that are now recognized by UNESCO.

The largest prehistoric cemetery on the Balearic Islands dates back over 2,500 years.

This abandoned, turn-of-the-century astronomy hub is now the subject of more photographs than it ever took.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

The little church's beautifully frescoed ceiling has earned it the nickname “the Sistine Chapel of Madrid.”

A once-secret library of Freemason history in Catalonia.

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

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

A beautiful but toxic fountain of mercury.

The 2,000-year-old pieces of metal are an ancient soldier's military discharge papers.