An old abandoned mining town in The Adirondacks where Theodore Roosevelt first learned of the shooting of President William McKinley.

This memorial in the Adirondack wilderness honors the accidental death of a Scottish entrepreneur.

An ancient glacial pothole waterfall in the heart of the Green Mountains.

The Vermont grave of a 4,000-year-old mummy prince.

Dispersed across 45-acres, 39 structures house a massive collection celebrating American Folk Art.

In order to save this beloved rock, locals blew it up and put it back together piece by piece.

This massive boulder is inscribed with the story of a sensational hostage negotiation dating back to Colonial times.

Within the former ghost town of Cisco is a carefully restored tiny town with one resident and its own art residency.

This raised bulls-eye visible from space was the subject of an intense geologic controversy.

Few things look more out of place than the electric blue ponds in the reddish-brown desert of Utah.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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

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

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

Perhaps the most scandalous statue of America's first president.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

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

D.C. once had its own tiny rival to the New York Stock Exchange.

A line of blue paint marks the route of the inaugural parade.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.