Since it formed millions of years ago, this cave system has been a sacred burial ground, a Prohibition-era speakeasy, and the center of an amusement park.

A historic landmark and museum filled with curious objects representing the history of Key West.

The maximum security facility was once thought to have "the bloodiest 47 acres in America."

What was once a presidential estate is now an exotic menagerie and home to the Budweiser Clydesdales.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

Look closely and you’ll notice that the color changes a third of the way up the tower.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

Perhaps the most scandalous statue of America's first president.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

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

Not to be confused with the iconic New York City skyscraper, this Chicago building is a vibrant hub for artists.

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

This historic hotel invented the chocolate brownie.

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

A former waterfront market is now in the center of town due to some interesting Boston engineering.

This landmark cemetery in Boston was created more than 300 years ago.

The site of Paul Revere's historic two lantern warning.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

An enormous, inside-out glass globe built in 1935.

The only home that Alexander Hamilton ever owned has a history almost as troubled as his own.

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.