Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

The house that Frank Lloyd Wright "(shook) out of his sleeve at will" at the age of 86.

A model of a dinosaur that was named for Andrew Carnegie stands outside the museum that also bears his name.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.

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

This quarter-mile tunnel under the Bluff in Pittsburgh bends at a 45-degree angle.

Meet your friends, marry your true love, or tell your enemies to kiss your butt under this historic Pittsburgh timepiece.

One man's real life disfigurement inspired a lasting local legend surrounding an eerie tunnel.

Memorializing an American tragedy of massive proportions.

Steepest flood safety railway in the entire world.

This dramatic rail curve was once the target of a failed Nazi attack.

A dozen U.S. presidents have stayed at the historic resort, which was known as James Buchanan’s “Summer White House” from 1857-1861.

The site where nine miners were trapped underground for over 77 hours in 2002.