A self-built castle made by a mysterious man.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

The body of St. John Neumann and his collection of hundreds of relics, on display in a Philly church.

This meticulously extracted nervous system allegedly came from a 19th-century custodian who donated her body to science.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

Where America's first doomsday cult awaited the end of the world.

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

One of the last functioning antique elevators in Chicago.

An avant garde art museum at the University of Chicago.

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

This unauthorized stone mermaid was secretly carved out of public stone before being permanently preserved.

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

The subtle science of a master molecular gastronomist.

A Bibliophile's Dream.

A monument to the art of slicing people open.

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

This morbid, delightful curiosity shop offers everything from animal bones to human teeth.

A Florida college boasts the world's largest single-site collection of structures designed by Frank Lloyd Wright.

The famed architect designed this Minnesota gas station of the future with a lookout tower.

This twice-relocated "Usonian" home is among the smallest built by master architect Frank Lloyd Wright.

Most historians agree that the so-called "Gentleman Pirate" wasn't much of either of those things.

A beautiful Victorian-era cemetery, complete with a miniature village.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

One of the oldest used bookstores in the U.S. has been selling antiquarian treasures since 1825.