One of many reminders of Tesla's scientific contributions overlooks the falls which inspired him.

A monument to a Polish general who fought the American Revolution and became the "Father of the American Cavalry."

A natural gas leak provides a flickering flame beneath a waterfall.

America's smallest national park site is the former residence of exiled Polish national hero Thaddeus Kosciuszko.

Alexander Hamilton’s creation caused quite a bit of controversy.

This elaborate towering structure was once famed for its revolutionary height.

This beloved marketplace mascot poops money and grants good luck.

Yo, Adrian!

This sculpture of a fisherman spent six years at the bottom of the Schuylkill River.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

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

This spot memorializes one of the greatest plays in NFL history, unless you happen to be a Raiders fan.

A retrofuturistic art installation in the Pittsburgh Airport.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

There’s a special club house at the top for the bell ringers.

The national park was once a plantation estate.

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

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

The U.S. Fish Commission’s effort to mass produce carp.

An overlooked memorial honoring the local Washington residents who died in World War I.

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

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