Only intact Ichthyosaur skeleton in the United States.

This cave was hidden for thousands of years, storing the worldly goods of ancient Native Americans.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.

Its dark depths conceal millions of rare, delicate crystal formations.

The ruins of a military outpost from the 1860s form the centerpiece of a Nevada state park.