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

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

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

The oldest continuously occupied public building in the United States.

A small side chapel in Santa Fe's basilica is home to the oldest statute of the Virgin Mary in North America.

Two tall rocks sit at the center of this site, once the home of a large Ancestral Puebloan community.

A dangerous narrow-gauge railroad once traced a route through this striking canyon.

A glimpse of a waterfall is reached by a steel catwalk along a slot canyon located in an Ouray city park.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

Legends surround this jagged rock formation in the New Mexico desert.

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

The hallowed remains of a 900-year old Ancestral Pueblo great house.

This spectacular track has run continuously since 1882.

A hotel with a rich Wild West history of miners and bootleggers.

An antique narrow gauge railway line still running through the Colorado and New Mexico mountains.

These aggressively sustainable art homes look like something out of 1970's science fiction.

A multi-storied adobe complex has been inhabited for more than a thousand years.

A registered historic landmark shrouded in unsettling local legends.

Norway's oldest cathedral still in use.

An ancient instrument used to measure the waters of the Nile so Egyptian farmers would know whether to expect famine or flood.

Standing atop 2nd-century Roman ruins, this church is one of the oldest and most iconic in Old Cairo.

The medieval center of the Islamic world was also once the seat of Saladin's sultanate.

This ancient structure is widely thought to be the oldest intact pyramid in the world.