One of Philadelphia's largest murals resides hidden under this bridge.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

Step into a pastel time capsule where candy is truly dandy.

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

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

A brass and marble scale model of the solar system embedded in the concrete.

This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

A diminutive memorial marks the site of a successful assassination by a right-wing death squad in America's capital.

A public art jibe at one of the United States’ oldest and longest-serving senators.

Before founding the American Red Cross, Clara Barton had a tremendous humanitarian impact by locating thousands of missing soldiers.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

Railroad officials in the early 1900s sought to spare travelers the sight of Roman soldiers’ private parts.

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

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

A home that witnessed Civil War combat on the Sunken Road has the battle scars to prove it.

These trees are living witnesses to events that inspired poet Walt Whitman’s service during the American Civil War.

The Kirkland Monument remembers a selfless Civil War hero who braved the battlefield to give water to his dying enemies.

This estate on the banks of the James River was home to a Founding Father, two presidents, a famous bugle melody, and what some say was the actual first Thanksgiving.

John Tyler never got to be buried at his beloved home, but every pet his family owned since has been.

Affectionately known as "Lord Bot," this historic statue has a cult social media following and rightly claims to be “the most metal inhabitant of the Wren Yard.”

Mass grave of 50 unidentified French Soldiers who died at the Siege of Yorktown, 1781, that gave victory to the American Revolution.