This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

The highest point in Delaware is located under a trailer so this marker across the street will have to do.

Outsider art meets paleontology at this roadside reptile repository.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

A Civil War Museum with some notable medical antiques.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

A labor of love built by local hang-gliding enthusiasts, this ideal launch spot was outlawed by the authorities and has since been largely abandoned.

A pre-Industrial Age iron furnace and the site of a nearly-forgotten piece of Black history.

Bizarre Cavern.

A monument marks the location of the first successful steamboat demonstration.

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

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A musical instrument played by the sea.

The first American department store, and home to the largest operating musical instrument in the world.

The last of Philadelphia's wood-paved streets is now a landmark of terrible engineering.

A layered tribute to the work of mosaicist Isaiah Zagar.

The famous winding walk at Chartres is surrounded in mystery and myth.

A museum dedicated to exhibiting remarkable outsider art.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.