The former home of Samuel Clemens and family remembers the happiest period of the author's life.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

Unrepaired walls from a 1920 anarchist bomb attack.

The house that Frank Lloyd Wright "(shook) out of his sleeve at will" at the age of 86.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

The only remaining piece of hull of the most decorated US ship of WWII is this giant name plate.

A museum dedicated to exhibiting remarkable outsider art.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

The final resting place of the tragic king and queen of the Jazz Age is tucked away in a small Maryland graveyard.

The "lovely red Vega" of the legendary record-settling pilot.

100 massive sculptures in the Hudson River Valley.

The only intersection in America where the buildings on all four corners were built pre-Revolutionary War.

The Hudson River School comes alive at this palatial estate.

America's first federal monument.

An original apothecary from 1792.

The final resting place of two (or three) presidents, one vampire, and 18,000 Confederate soldiers.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

A Civil War Museum with some notable medical antiques.

The privately owned cemetery that holds room for Washington's finest when they step down from life.

Art deco landmark on the outskirts of Washington, D.C.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

Home to items never before seen by the public.

Mysterious 500-year-old tapestries depict a unicorn hunt.

A museum designed by and dedicated to P.T. Barnum in the town where he is buried.