This advertisement for talcum powder was painted on the rock face and has since defied removal.

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

Built in the 1850s, this church was of the first five churches constructed in Harper's Ferry.

This shale formation along the Appalachian Trail once inspired the third president of the United States.

A total of 14 men held the title of "president" before George Washington—their historical legacies are enshrined in the lobby of a hotel.

George Washington's dentures and Queen Victoria's dental instruments are in the nation’s official museum of the dental profession.

One of the oldest anatomical theaters in the U.S. still in use was once the site of an infamous cadaver riot.

The "Sultan of Swat" once attended a school at the site of this baseball field.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

An eerie diorama that captures the majestic nature of a few prehistoric-looking beasts.

Creating this diorama spurred naturalist Carl Akeley to begin advocating to protect the apes.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

Built as a gift to the hottest tastemaker of the time, these hidden quarters remain an Art Deco showpiece.

Two large-scale sculptures of Adam and Eve greet visitors in the nude at the Time Warner Center in NYC.

Once considered the height of medical modernity, this structure is now the oldest remaining component of Roosevelt Hospital.

Slyly buy a shake in the Parker Meridien lobby.

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.

Politicians, bureaucrats, and military officers gathered in this field near the Capitol to settle their disputes with blood.

A swimming hole in the historic industrial quarry that supplied the marble for the Baltimore Washington Monument.

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

A winding district gerrymandered into the shape of a mantis.

Crammed into a Baltimore row house is an oddities shop that sells everything from skulls to dead insects.

This free, take-a-book shop seems like a trick but isn't.

This beloved Baltimore spot features caged dolls, a giant Pez collection, and many, many mannequins.