A preserved 18th century homestead in Western Pennsylvania marks the spot where the Whiskey Rebellion began.

An artificial crater field that trained astronauts for lunar exploration.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

This elaborate towering structure was once famed for its revolutionary height.

Yo, Adrian!

A clone-tree in Washington Square Park sprung from seeds that went to the Moon and back.

Georgia's first brewery is also one of its oldest surviving buildings.

Constant erosion has created a surreal landscape of bleached and preserved fallen trees.

An overlooked memorial honoring the local Washington residents who died in World War I.

It was once the base for a series of domestic terror attacks.

There’s a hidden military meme engraved on the World War II Memorial.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

Largest Roman Catholic church in North America.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

Home to items never before seen by the public.

When you visit his grave, be sure to rub the Great Emancipator's nose for good luck.

This collection honors the iconic, and proudly American lighter that just won't quit.

Memorializing an American tragedy of massive proportions.

A museum commemorating the Donora Smog, which killed 20 people in October 1948 and sparked national outrage over air pollution.

A restored Pittsburgh house of God has been converted to a marvelous house of suds.

This spot memorializes one of the greatest plays in NFL history, unless you happen to be a Raiders fan.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

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