This 19th century machine put animals (including humans) in boxes to study how they metabolized calories.

Priceless space junk on display in front of a local Dairy Queen.

Little has changed in the way that this mill operates since the 18th-century.

The god of wine stares out at passersby on this busy Pittsburgh thoroughfare.

In the parking lot of a fast food restaurant, a statue memorializing a prolific bull elephant.

This one-room cabin where the young colonel slept during the French and Indian War.

Maryland's first (and last standing) toll house on America's first federal road established the state as the "Gateway to the West."

The first blast furnace in the United States that used coal and coke fuel instead of charcoal to make pig iron.

Pennsylvania's highest point is spotted with boulders which were pushed to the surface by nothing but cold.

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.