A relic of the Cold War in Chicago.

A bloodstain from "the wound of the transverberation of the heart."

World's second largest particle accelerator, where nature reveals its secrets.

In the Shawnee National Forest, amazing rock formations peer through the treeline.

This elaborate Hindu temple is located in a Chicago suburb, but looks like it was transported directly from India.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

This surprising gem is a world-class archeological museum hidden at the University of Chicago.

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

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

Each of these gorgeous, intricately decorated rooms is painstakingly crafted to the scale of 1 inch: 1 foot.

A science teacher's dream.

A shining sculpture made of 3,115 lights, the number of visible stars in the Northern Hemisphere.

The only Bahá'í house of worship in North America and one of only a handful worldwide.

A century-old hotspot for jazz, frequented by everyone from Charlie Chaplin to Al Capone.

A Bibliophile's Dream.

A speakeasy takes on Chicago's drinking culture.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

A well-preserved Ancestral Puebloan ruin tucked beneath a desert cliff.

A haunted hot springs hotel that went from healing retreat to asylum before it was restored.

An abandoned relic of the city's failed experiment with below ground transit.

A diverse, expansive nature preserve in northeastern Kansas.

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

This remote island in Iowa was abandoned after being devastated by flood.

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