Steepest flood safety railway in the entire world.

Pennsylvania's own Roswell-style UFO mystery.

Memorializing an American tragedy of massive proportions.

The first declared National Monument in the United States.

A take-out restaurant that only serves cuisine from countries with which the United States is in conflict.

Hundreds of protractors affixed to surfaces all over the city.

Found art has transformed this Pittsburgh neighborhood into a psychedelic dream.

The echoes of a railroad town that solemnly mark the end of the line.

Towering basalt columns, a creation of fire and ice.

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

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.