The last remnants of Fort Pitt also hold the distinction of being the oldest structure west of the Allegheny Mountains.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

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

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

The museum calls itself the "National Museum of the Paranormal" and is full of eerie oddities.

Turnip-shaped island just off the Michigan shore in Lake Huron.

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

A ship that lived many lives under many names is now known merely as the "Ghost Ship."

A chilling disappearance (and rescue) of a child uncovers a geological mystery.

A museum that houses the world's largest collection of ventriloquism dummies.

The largest earthwork effigy in the world.

A suspended garden, now gone, once hung in the middle of this abandoned church.

Nonprofit art center that promotes outsider, intuitive, and self-taught art.

A century-old network of freight tunnels underneath the city's historic business district.

A gothic church spire sits atop this skyscraper, the tallest church in the world.

Over 1,000 pieces of one of the most niche art objects imaginable: the glass paperweight.

To find the "unicorns of the deep" you've got to go downstairs.

A memorial for an outsider theorist who believed that the planet is actually hollow.

This stunning gothic ruin was a casualty of the Indiana steel industry crash.

A single handprint, which, according to Ohio State University legend, cannot be scrubbed off.

A retro walk through the history of the tube.

The entrance to this sinisterly named tunnel hides behind a Tim Hortons.

Inside this wonderland of weird, visitors are treated to a collection ranging from skeletons to haunted artifacts.

This pair of eccentric Ohio castles were built by a pair of brothers who wanted to bring a bit of class to the Ohio wilderness.