Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

A natural gas leak provides a flickering flame beneath a waterfall.

A New York garbage depot holds a secret collection of weird and wonderful refuse.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

The first declared National Monument in the United States.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

The longest continuous lava tube in Oregon.

An institution that preserves the history of institutionalization.

This lake in the Cascades lives up to its name, disappearing down a hole every spring.

Treehouse motel and treehouse-building school.

This central Nevada cave is the spiritual home of ancient and enigmatic pictographs.

This cave was hidden for thousands of years, storing the worldly goods of ancient Native Americans.

The most magnificent bottle house in a town strangely full of them.

The Wonder Road aka Doobie Lane, a mile-long strip of dirt road filled with folk art.

Mine your own precious stones.

Eulogizing an unknown man's unusual demise.

Preserving the remains of Native American cultures which otherwise would have been submerged behind Hoover Dam.

A gothic palace of endless stalagmites and pseudoscorpions waits within one of the world's most beautiful caves.

Experience a charming 1930's version of "infotainment."

These banned cigarette vending machines now sell little pieces of pocket-sized art.