Once the world's largest reinforced concrete structure, this abandoned bridge now beckons urban explorers.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

This Boy Scout retreat acted as "Friday the 13th"'s original Camp Crystal Lake.

Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

The first neighborhood to implement the Garden City model in its suburban planning.

Seller of surplus nuclear research materials.

On the edge of the Valles Caldera National Preserve, these rock formations create an eerie landscape.

The oldest continuously occupied public building in the United States.

A natural formation that resembles a camel resting in the New Mexico desert.

This opulent Pueblo Deco movie palace melds Art Deco and Native American motifs.

The 7,000-year-old calcium carbonate formation creates a magnificent natural bridge.

Eat like pre-Columbian Native Americans in this New Mexico restaurant within the Indian Pueblo Cultural Center.

Its history includes dinosaur fossils, cattle rustlers, Georgia O'Keeffe, and a mythical giant rattlesnake named Vivaron.

A burnt-out motel with priceless Native American artwork in the basement, redeveloped into apartments.

This museum started as a collection of Manhattan Projects and continues to add exhibits as they are declassified.

One of the American Southwest's most extensive collections of Navajo rock art.

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

A unique geological area spiked with wind-carved rocks that resemble teepees.

This quirky hot springs town known to locals as "T or C" was named after a radio show.

The official atomic museum of the United States explores the explosive and productive history of a much maligned energy source.

A small metropolis of Pueblo cave dwellings have been carved right into the hillside of this national monument.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."