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

This stained glass window designed by Tiffany Studios is hidden behind the circulation desk of a public library.

A historic recreation of the golden age of the Erie Canal, abandoned for some time, slowly being restored.

A sewing machine tycoon built this miniature castle for the people and to beautify a lakeshore.

This stone gatehouse was once the entrance to a historic mountain resort, and it had a cameo in a cheesy cult horror movie.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

A reservoir of vintage pinball machines and arcade games for the nostalgic and thrill seeking.

Marie told fortunes from her small stand on the Boardwalk for decades, including to a young Bruce Springsteen who would busk outside her booth.

Vacant Beaux-Arts buildings that serve as reminders of a beach town’s glory days.

The lost town of Neversink, sunk by New York City.

An abandoned dollhouse factory.

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

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

Commonly acknowledged as the only public monument to the Devil himself.

This fascinating and poignant museum chronicles every imaginable aspect of Spanish colonialism in the Americas.

This funky former tobacco factory is one of the most striking examples of Madrid's cultural diversity.

A lush indoor jungle fills this bustling Madrid transportation hub.

The largest known open fault in the United States is basically a giant natural refrigerator.

The dairy farm in upstate New York where nearly half a million people gathered for three days of peace and music in 1969.

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

This giant monument of the RCA mascot is a beloved fixture in Albany, New York.