A collection of objects supposedly singed by the hands of souls in purgatory.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

Six tiny houses built for working class people form the largest intentional cluster of Wright homes anywhere.

The pile of books behind the dignified writer gave the statue a most undignified nickname.

Where Venice's gondolas go for a tune-up.

Golden cobblestones remember a time when this small alley was used to avoid having to give a Nazi salute.

The footprint of a frustrated devil in Munich's Cathedral.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

A surreal statue honoring Prague's favorite literary son.

The hidden lair of an alchemist rediscovered in a 2002 flood.

Tens of thousands of ancient rock carvings hidden in the heart of a French national park.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

Illegal drag racing two stories beneath Chicago’s streets.

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

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

This historic hotel invented the chocolate brownie.

The twin towers in this Chicago fountain use 50 foot tall video screens to spit on people.

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

A gothic church spire sits atop this skyscraper, the tallest church in the world.

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

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