Engraved in stone here are the signatures of everyone who signed the Declaration of Independence.

The Lincoln Memorial has inspired many, even though a word on the inscription appears to be spelled incorrectly.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

The 28,000-year-old specimen is remarkably intact.

The National Park Service’s best-kept secret with views that rival any in D.C.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

Tucked into Pittsburgh’s North Side, the Mattress Factory is a labyrinth of permanent, room-sized installations where artists transform entire spaces into mind-bending, immersive worlds.

This riverside restaurant delivers elegant dining in a historic 1901 train depot. 

A comprehensive archive of Hallmark Holiday ornaments.

These disused steel furnaces are now haunting ruins that may one day be a national park.

When oil was discovered just outside of Pittsburgh, the city became home to this regional stock market.

A retrofuturistic art installation in the Pittsburgh Airport.

These enduring murals depicting a distinctly Marxist tribute to capitalism could not even be defeated by McCarthyism.

The world’s largest Masonic temple was saved by the White Stripes.

Inside the Wayne County airport is an amazing collection of lights and sounds.

The 80-foot tire that looms over Michigan's I-94 was once a Ferris wheel in the New York World Fair.

The only surviving prototype for Buckminster Fuller's house of the future.

A sealed test tube said to hold Thomas Edison's dying breath was given to the inventor's friend and mentee, Henry Ford.

Pittsburgh’s largest and most detailed model train display began as one WWI veteran’s hobby.

Don't get it twisted: This is the oldest pretzel bakery in the United States.

This is the spot where the bloodiest battle in the American Civil War may have started.

A jukebox headstone marks the grave of the Cleveland disc jockey credited with coining the term “rock 'n' roll."