An 18th-century Spanish watchtower made entirely of seashell and concrete.

This ancient settlement contains some of the largest earthen mounds in North America.

The oldest operational cathedral in the U.S. has one shell of a way of projecting speakers' voices.

This site is dedicated to a candidate for sainthood and contains personal items including his cilice and lead coffin.

A Rodeo for Prisoners.

The famous author's birthplace is preserved in a town that he once described as narrow-minded.

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

No one knows how many bodies are in this vault in a Chicago public park.

A journey begins with a single step, and for many, the road-trip of a lifetime started at this Chicago intersection.

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

A hollow cement depiction of time's inexorable effect on the human body.

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

Chicago’s incendiary role in the labor movement.

This bronze sculpture on a former squash court marks the secret origins of the Atomic Age.

A 400-foot-tall tall map of Chicago makes this once-ignored building stand out.

The last masonry skyscraper ever built reveals a transitional moment in architectural history.

A spectacular remnant of an Adler and Sullivan masterpiece that was destroyed in 1972.

Once at the center of U.S. finance, the historic Trading Room was meticulously recreated piece by piece and rebuilt in the Art Institute.

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

A strange and haunting monument of unknown origin in the historic Graceland Cemetery.

This landmark of the Chicago silent film industry may not be in the picture business anymore but it still stands proudly.

A haunting statue called "Eternal Silence" has quite the reputation among visitors with active imaginations.

This memorial plaque remembers a strangely shallow maritime disaster known as "Chicago's Titanic."

Home to a protest movement, a bombing, and a dramatic change in labor history.