This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

This museum was once the home of industry titan Matilda Dodge Wilson.

No one really knows how these old hobby horses got here, but the herd keeps growing.

An allegorical statue of a giant pregnant woman representing justice and truth.

A huge museum of much more than just agriculture displayed in a princess's palace.

Railways may have forged this quintet of lovely tunnels, but now they are open to hikers.

Faces carved into the cliffs create an otherworldly walking trail.

Spectacular mineral formations fill these caves, which have been used for everything from smoking meat to stashing illicit liquor.

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

A throwback train ride transports passengers through one of the lesser-known national parks in the country.

Beside a busy highway, a colony of Great Blue Herons raises hundreds of offspring each year.

Where the oil industry began.

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

"Where the ducks walk on fish."

The Pennsylvania landscape depicted by a quarter mile of mosaics made from used road signs.

This massive airship factory is so large that it has its own indoor weather.

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

Steepest flood safety railway in the entire world.

The spectacular collection of one of the world's best woodcarvers.

Mausoleums, astronomy, and animatronic dinosaurs at this memorial to an assassinated American president.

The site of Neil Armstrong's first flight is marked by a full on replica of the moon landers.

A miniature golf course crafted inside the world's largest simulated cave.

The largest burial mound in the United States holds the remains of prehistoric West Virginians.

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