A winding path built in secret on the edge of the continent.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A 140-year-old castle with underground caves hidden in San Francisco.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A swamp that was the site of prehistoric water burials also managed to preserve its corpses for millennia.

Town of spiritualists and mediums in Florida.

A mega theme park-wax museum mélange containing all things biblical.

Human skulls and a stuffed goat made into a rocking chair can be found at this strange little store.

Remarkably realistic Florida shoal bass "swim" inside this large globoid sculpture.

Bronze statue marks the spinach capital of the world.

A small museum dedicated to the whimsical tool that turns sugar cookies into works of art.

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

A historic neighborhood church is reborn as a psychedelic arts collective.

This grave marks the passing of a historic Jane Doe whose identity remains a mystery to this day.

Four bald cypress trees in Lafayette Square, across from the White House, mark the southern edge of a 100,000 year old cypress swamp.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

At 207 feet, one of the world's longest continuous escalators.

A super-sized promotional trick that is now a D.C. landmark.

The most decorated dog of World War I is preserved in the Smithsonian.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

The romance of early commercial flight still fills this Art Deco destination.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

The United States Capitol's former columns still stand.