A little-known subterranean street runs under some of the best-known buildings in Chicago's River North.

A display of magnificent stained glass windows is the first exhibit of its kind.

Chicago's largest cemetery is full of beautiful Victorian monuments and more than a few ghost stories.

A once-booming Mississippi River town with a history of racial violence is now eerie and mostly abandoned.

Shop of curiosities with a dinosaur museum tucked in its basement.

This unauthorized stone mermaid was secretly carved out of public stone before being permanently preserved.

A science teacher's dream.

An enormous park-like oasis, full of famous Chicagoans' graves.

A giant bronze coil of feces is both a tribute to doggie defecation and a reminder to pick it up.

A monument to the art of slicing people open.

The abandoned bathhouse is all that remains of the hot springs considered Florida's original tourist attraction.

Over 100 concrete munitions bunkers are all that remain of a Pennsylvanian village seized by the US government.

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

An abandoned stretch of highway, deteriorating next to the operational one.

Collection of trolley cars in the woods represent one man's attempt to preserve transportation history.

These rows of World War II-era bunkers were the scene of some of the infamous Mothman sightings.

This abandoned dream castle and its cemetery look out over the city that once inspired their creation.

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

An abandoned asylum where patients have been forgotten but their possessions remain.

This abandoned subway station can still be seen on regular commuter trips.

Deep under Manhattan is the largest construction project in city history. So far, the project has taken the lives of 23 workers, or "a man a mile."

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

The loneliest island in New York.

Abandoned power station once home to a squatter community, now being developed into an arts center.