An 18-mile-long tunnel for sewage waste will soon wind within the bowels of Washington, D.C.

The towering figures were created from the cemetery's fallen old-growth trees.

Designed to commemorate the founding of the first settlement in Delaware.

The "All-Seeing Eye of God" symbol on this library is a clue to one of the many former lives of this building.

This shale formation along the Appalachian Trail once inspired the third president of the United States.

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.

The oldest surviving one-room schoolhouse in Montgomery County, Maryland.

Baltimore's first skyscraper may be home to the inspiration behind pulp fiction's most celebrated bird.

The childhood home of the Sultan of Swat is just a line drive away from Oriole Park at Camden Yards.

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

Constructed by the younger brother of George Washington.

Enjoy dishes that founding fathers once ate at this Colonial Williamsburg pub.

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

The largest cemetery for enslaved people in Loudoun County was almost lost to history, if not for the research of a minister.

A "hospital" where people went to be quarantined, die, and be buried in the yard.

The last remaining building in Washington, D.C., built by H.H. Richardson, one of America's most iconic architects.

This historic building is now home to the Public Access Corporation for the District of Columbia.

A street in front of NASA's D.C. headquarters has been named in honor of the Black women who were essential to early spaceflight.

The historic home of an educator, abolitionist, activist, and poet.

The former home of Lillian Evans Tibbs and her grandson, Thurlow Evans Tibbs Jr., whose prodigious contributions to music and art spanned more than 90 years.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

Home to two notable early-20th-century Black educators, Lucy Slowe and Mary Burrill.

Surrounded by a verdant garden and a backdrop of ivy, a monument to beloved poet Khalil Gibran stands outside of the Lebanese embassy.