The world's longest known cave system.

See the nearly two-century-old ruins of pre-railroad America at the former site of a lock on the Ohio and Erie Canal.

Home to several unusual artifacts, including a huge painting of George Washington.

Dozens of striking Indian symbols cover the second-floor hallways of this rural courthouse.

The world's tallest doric column is this Ohio monument to a naval victory in the War of 1812.

An abandoned munitions factory with a shot tower continues to wage war on the surrounding environment.

But did the famous feminist and abolitionist ever really say those iconic four words?

This whimsical campus lawn is dotted with large sculpted numbers and hidden mathematical formulas.

The permanent home of Elektro, the celebrity automaton of the 1939 World's Fair.

A county library in rural Ohio houses one of the finest mineral collections in the world.

Unique collection containing a wide and curious range of contraceptive items.

Piled high inside this warehouse and coffee shop are salvaged goods that span every corner of the globe.

A pop-culture attraction outside of Dyersville, Iowa, hits a home run.

A half-mile long and three stories high, this bridge over the Des Moines River Valley mimics a descent into a mine shaft.

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.

The very isolated Charity Island Lighthouse has been watching over Saginaw Bay since 1857.

The restored ferry is now a dockside museum and a unique bed and breakfast.

The smallest useable chapel in Michigan is five-by-eight feet and has seating for three.

Outside Grand Valley State University, you'll find a bench upon which many were said to have sat according to the fictional Kcymaerxthaere, waiting for a guide of time.

Reason for Michigan's potential diamond mine.

At HopCat, a marker honors fictional creatures with the ability to travel the missing dimensions of Kcymaerxthaere.

Detroit’s downtown castle is one of the oldest structures in the city.

This national park dedicated to the tallgrass prairie ecosystem still displays its military past.

A sprawling outdoor museum filled with larger-than-life works of art.