Ancient pueblos built into the base of a natural canyon wall.

The final resting place of the businessman-turned-astronomer who helped discover Pluto stands near his observatory.

This ghost town was once a cult-like religious utopian settlement.

The giant stump of the once towering cottonwood where Ute people held tribal meetings.

The highest bridge in America was built for an almost unnervingly small amount of money.

This razorback ridgeline has doubled as a scenic drive since the early 1900s.

Fresh wooden posts have been added to ancient holes to recreate a primitive henge clock.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

The real-life site of Ichabod Crane's infamous gourd attack.

Every year model trains zip through a miniature New York City that's now 150 landmarks strong.

This plot of old-growth forest is the largest surviving remnant of New York City's original woodland.

This huge work of functional public art replaced a landfill in New Jersey's Meadowlands.

This Bronx apartment building is officially recognized as the birthplace of hip-hop.

This hidden oasis features a stunning view of the Hudson River and the Palisades from a castle-like museum.

A large boulder marks the place where the island of Manhattan was purportedly "sold" to the Dutch.

Abandoned Coast Artillery fort now serves as graffiti canvas and sightseeing vantage point.

This 24-acre park offers a place for meditation in the midst of Sedona's iconic red rocks.

The United States's largest hand-dug well is topped with a state-of-the-art museum.

The final resting place of more than 200,000 people, this is one of the largest cemeteries in Europe.

Once the largest rope factory in Greece, this abandoned plant now stands like a ghost of industry past.

Quite possibly the oldest love poem known to humankind.

This crucial gathering spot along the "hippie trail" still displays old notes between traveling beatniks and backpackers.

The maze-like transportation hub contains abandoned areas, derelict stores, and a resident bat colony.

The only quarter of the Old City not dedicated to a major world religion.