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

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

It should come as no surprise that the world's largest artichoke lies in the town that calls itself the "Artichoke Center of the World."

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

Odd, decrepit fountain honors Chicago author who had mixed feelings about his hometown.

The faint remains of a Polish news empire still linger.

This shop for all your super spy needs hides an educational secret.

These molds for fiberglass statues have formed an eerie, accidental sculpture park.

Once adorning a New York skyscraper, these reclaimed ruins now haunt an Indiana park.

A monument to the egos of two railroad magnates that fell into decline along with their careers.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

Nope, not Washington Irving's house.

Rumored to be the famed pirate's lookout tower, this historic stone structure is now just watching for tourists.

The one-time epicenter of American songwriting is now a little remembered Manhattan commercial block.

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

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

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

This Tennessee museum is dedicated to a tragic railroad hero who inspired the famous ballad that bears his name.

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

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

Wisconsin's most celebrated export gets the royal treatment on I-94.

Half-sized replica of the Leaning Tower of Pisa built to honor Galileo.

An antiquated German apothecary on Chicago's North Side.

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