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 overgrown Illinois water park offers a whole new type of adventure.

This grave in a ghost town cemetery marks the death of a witch on a day that never happened.

This modest post office sits on the site of H.H. Holmes' famous murder castle.

Combination beer garden and music venue in the heart of Wicker Park.

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

Built to house a chapter of the Knights Templar, this grandiose building is a relic of Freemasonry in Chicago a century ago.

River pirates, murderous bandits, and serial killers used this Illinois cave as their debauched hideout.

Cemetery featuring rare glass-fronted columbarium.

Years of archaeology, just chillin' by the water cooler.

Beloved bar home to musicians of all eras and reputations.

The world's only known button museum.

An outdoor urban gallery of large-scale artworks by the world's most influential street artists.

The site of the first couple's first kiss is commemorated by the most adorable presidential monument ever.

This museum celebrating the almighty dollar lets visitors literally stand in the shadow of a million bucks.

This alley in downtown Chicago held the bodies of over 600 people after the fateful Iroquois Theatre fire.

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

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

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

These abandoned grain silos and tunnels are an urban exploration dream.

What's left of the ruins of the 1893 Columbian Exhibition, or World's Fair, also known as the White City.

A science teacher's dream.

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

All of Chicago's wood-paved streets are long gone but two alleys remain.