The whole world in one water tank.

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

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

Captain John Smith thought these cliffs were amazing in 1608 but sharks thought so 20 million years before him.

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

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

The ruins of this long-abandoned unsuccessful gold mine can still be found.

The land is home to swimming ponies and a legendary 18th-century treasure.

An astounding collection of medical specimens, including bits of President Lincoln.

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

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

This historic boathouse was constructed using salvaged lumber from burned barns.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

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

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

A portal into the bricked up canal that runs through the heart of Washington D.C.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

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

These abandoned waterworks are crumbling into the Potomac River.