This massive library holds what was once the largest book collection in the world.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

Arguably the best example of an authentic Dutch windmill in the United States, rivaling its counterparts in the Netherlands.

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

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

A science teacher's dream.

What was once one of the country's largest confectionary plants is now an abandoned ruin, but is still pretty sweet.

This urban drawbridge gained eternal pop culture fame when the Blues Brothers jumped it while it was raised.

This cheerfully-named branch of the Chicago River is the fetid result of years of blood, entrails, and meatpacking waste.

A turn-of-the-century architectural marvel built on healing mineral springs and salt licks.

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.

A Museum of Holography frozen in 1974.