Over a thousand feet beneath the Detroit streets is a subterranean metropolis few are allowed to enter.

This shallow cave got its name from copious amount of human bones found inside.

Collective made up of artists, musicians, and activists.

The remains of a religious colony, its amusement park, zoo, and baseball empire.

This protected area in Lake Huron contains some of the world’s best-preserved shipwrecks.

Concrete igloos standing across from what remains of the Michigan Central train depot.

Dilapidated Mayan-themed ballroom was one of Detroit's most popular venues through the 40s.

This lovely public park has an intriguing past and unique wooden bridges made of concrete.

The museum moved on, but the diorama remain.

The concrete shell of an industry giant remains as a playground for graffiti artists, auto scrappers, and paintball warriors.

A park and memorial dedicated to the victims of the deadliest school massacre in American history.

A quaint miniatures museum that turns its focus towards the lives of Americans in a simpler time.

Former self-sufficient mental institution now a planned community.

Though its celestial ceiling is impressive, the true star is the vast collection of French books.

The world's oldest bookshop still in operation.

Eclectic collections, artwork, and some feline friends fill the writer's former home.

Science fiction's grandfather has a fittingly marvelous tomb.

The world's largest collection of materials relating to lesbian history is housed in a Brooklyn townhouse.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

Made of giant chains and hung with shackles, this iron cross honors those unknowns who perished under American slavery.

A museum within a museum, devoted to history's most questionable medical devices.

This Austrian museum celebrates the work of famous forgers and their inimitable imitations.

Brain collection and database that narrows the gap between man and animal.

Center filled with hands-on displays served as a tribute to several astronauts with connections to the state.