Light still pours into the ruins of this ancient Islamic observatory.

A dark patch of the ceiling at Grand Central Terminal which was not restored is still stained brown by tobacco.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

Herbert Hoover's "Brown House" rural presidential retreat was a PR disaster amid the start of the Great Depression.

A bunker "with enough U.S. currency to replenish the cash supply east of the Mississippi" in the event of nuclear war now protects nitrate film.

This pre-Revolutionary War grist mill ground corn and flour for soldiers in seven American wars.

A local farm's collection of unusual structures from a now defunct storybook amusement park.

The 320-year-old tree that greeted General Lafayette and rerouted an interstate highway.

A faded sign from the 1920s remembers Baltimore's resistance toward banning alcohol.

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

Washington's iconic carousel has a nice piece of Civil Rights history.

Home to items never before seen by the public.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

FDR's Art Deco hospital tower was hopelessly inefficient.

A priceless collection of the Nation's cryptologic history.

The palatial McDonald's that inspired Wesley Willis.

This softly rounded mansion was built without corners not to avoid evil spirits, but to make them more comfortable.

Near-constant high winds deform the trees on Spruce Knob, the highest point in West Virginia.

A 200-year-old bar with a cheeky name claims to have served Edgar Allan Poe his final drink.

The trials and tribulations of marking Poe’s grave.