Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

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

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.

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

The last remaining vestige of a popular 1999 public art display.

Each of these gorgeous, intricately decorated rooms is painstakingly crafted to the scale of 1 inch: 1 foot.

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

This historic hotel invented the chocolate brownie.

A military museum and library dedicated to the citizen soldier.

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

This awkward aquarium sculpture is one of the strangest statues in Chicago.

Rifle through images of skyscrapers, Worlds Fairs, and more in the largest public postcard repository in America.

To find the "unicorns of the deep" you've got to go downstairs.

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

An eccentric park and pool.

You can take a class, browse the library, or visit the lavish lair of an international men's humor society.

The 30,000-volume library is one of the world's most impressive poetry collections.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

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

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

A display of magnificent stained glass windows is the first exhibit of its kind.