This Pennsylvania cave holds evidence of the oldest known inhabitants of North America.

This eccentric mansion museum holds a impressive collection of rare and automatic instruments.

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

It would take 35 firetrucks to fill this enormous glacial pothole.

The Home and murder site of the witch of Rehmeyers Hollow.

A historic covered bridge is but one example of an oddly prevalent American urban legend.

America's first serial killer rests in anonymity.

This lush forest valley was once mined for lumber to the extent that it was once nicknamed "The Pennsylvania Desert."

The residents of the Neighborhood of Make-Believe live without much fanfare within the Pittsburgh Children's Museum.

This Philly landmark has a giant butterfly pavilion, three floors of insect displays, and withstood a $40,000 heist.

When the Austin Dam failed it destroyed much of Austin...and then it failed again.

There aren't too many operational funiculars around, but Pittsburgh has two!

A macabre farm reserved part of its 222-acres for dead bodies, all in the name of science.

In the early 1800s, surgery was also a show.

The oldest farmer's market in America is so ancient it was approved by the King of England.

The remains of a community that was forced to move for a dam that never materialized still rot in this Pennsylvania park.

The only way to see Pittsburgh is from the top of this lookout point, just like the ancient members of the native peoples did.

This hidden gem of a garden has one of the only surviving Victorian ferneries in America.

Dr Barnes' $25 billion private collection of art and arboretum.

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

This church in Pittsburgh is home to the largest collection of religious relics in North America.

In the bowels of a 19th-century brewery lurks a fine-dining restaurant offering an array of themed feasts.

This Old Testament garden features 100 plants from biblical times.

A mine fire has been burning under the deserted town since 1962, but this church is still going strong.