The well-preserved remnants of a bridge that once made up a WW1-era military railroad.

A piece of the Ludendorff Bridge, also known as Remagan Bridge, calls this military base home.

A superbly preserved example of Georgian residential architecture that was once home to one of the founders of Alexandria, Virginia.

One of the Treasury Building's original columns now sits as a garden monument in the middle of a busy military base.

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.

This field of concrete was once an active defense site armed with nuclear warheads.

This monument is dedicated to those lost on June 6, 1944, in the town with that day’s highest per-capita casualty rate.

The former home of the man whose radical ideas changed the nation.

A highway marker that honors a former spy plane pilot and local hero.

This little brick tunnel built by Confederate forces was used to conduct surprise attacks on the railroad.

The Pentagon is so large that it was planned like a city, complete with internal highway infrastructure.

This former Cold War missile control site played an important role in the creation of GPS.

The Pentagon sits on a former island that was in Virginia at low tide and D.C. at high tide.

America's second-oldest brick baseball stadium was home to a legendary WWII series that only sailors got to see.

The airport was once a Civil War battleground, and the earthwork defenses can still be seen today.

This twice-relocated "Usonian" home is among the smallest built by master architect Frank Lloyd Wright.

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

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

Once forgotten and built over, this historic Black cemetery now houses a poignant memorial.

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

This simple stone memorial remembers a secret, Geneva Convention-defying interrogation base from WWII.

This pun was simply waiting to come to life, and one defense contractor made it so.

The U.S. Army's giant warehouse of war art includes Hitler’s watercolors and Norman Rockwell oil paintings.

A lone historical marker off the highway and scattered debris are all that remain of this Cold War-era missile site.