A museum dedicated to the alleged Roswell Incident.

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

The world’s largest truck stop includes a barber shop, chiropractor, and a huge museum with antique trucks.

It may look like no more than a full-scale model, but every part of this full Space Shuttle stack had a working role in aviation history.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

This equestrian statue of Constantine the Great has been the subject of criticism for centuries.

Breathtaking and huge 430 year old maps of Italy.

Despite a legend that says this highest peak in Oregon was climbed in high heels scores of people have died on its slopes.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

2300-year-old Roman road connecting the empire.

Considered by many to be one of the most dangerous highways in Alaska.

This super-sized statue is the only public memorial to the deal that ended America's neutrality during World War II.

The sculpture's largest spire points directly toward the North Star.

A morbid gateway to an Alaska town prides itself on the hunting history it represents.

During the summer, surfers in Alaska take advantage of this inlet’s unusual water patterns.

Running under an entire mountain, the longest highway tunnel in North America is kept fresh using portal fans and jet fans.

North America's first frozen mummified remains of an ice age steppe bison, the 36,000 year-old mummy named "Blue Babe."

This WWII-era military installation once held an entire city within its walls - now, its walls are falling down.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

Four-story concrete hotel never opened to customers.

A trading post in the North Pole where children send letters.

The king of U.S. high points towers over every other peak on the continent.

Mind-blowing carvings and fantasy ice scenes grace the largest year-round ice environment in the world.

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.