This site contains overlapping ancient graveyards that existed about 1,000 years apart.

A pagan tradition of draping trees with rags eerily lives on.

One of the most important Celtic-Roman archaeological sites in Spain.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

A breathtaking and biodiverse wilderness in the mountain setting of Ernest Hemingway's "For Whom the Bell Tolls."

A magnificent, long-abandoned castle built in the wake of the reconquest of Spain.

A model solar system adds a celestial touch to this suburban park.

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

The abandoned ruins of America's first private zoo are open for exploration in the Catskills.

Home to the Titanic Historical Society's collection.

A distillery built on (and above!) mobster Dutch Schultz's Prohibition-era underground moonshine business.

A treasure trove of rare and fine fabrics from around the world.

Designed as a place for patients to take in the scenery, this tower has a dark history.

Founded by the famed children's book artist, this museum spreads an appreciation of the arts through picture books.

One of the most scenic falls in Massachusetts has a history of death and grim legend.

The first American home of the isolated, egalitarian religion has a trove of Shaker architecture and artifacts.

Three acres of mythology-inspired sculptures are visible from the highway.

A CT scan revealed the identity of this 3,000-year-old mummy that everyone erroneously thought was female.

The mansion home of author Edith Wharton.

A man used his Civil War-era fortune to build this sanctuary in memory of his wife.

The remains of this misplaced church were moved here stone by stone.

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

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.