The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

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

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

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

The "lovely red Vega" of the legendary record-settling pilot.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

This taxidermy horse was a Civil War hero.

Perhaps the most scandalous statue of America's first president.

The most decorated dog of World War I is preserved in the Smithsonian.

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

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

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

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

Also known as the Founding Church of Scientology.

A monumental statue of RCA's mascot now sits atop a historical society roof after a life of moving around.

The design of this historic domed church was influenced by Thomas Jefferson and intended as a statement of religious freedom.

An abandoned church gets a second life as a massive beer hall and event space.

One artist’s scheme to expand museum viewing hours into the evening led to the illumination of an entire city.

Once America's tallest structure, now a Baltimore landmark.

A museum dedicated to exhibiting remarkable outsider art.

A 200-year-old bar with a cheeky name claims to have served Edgar Allan Poe his final drink.

A faded sign from the 1920s remembers Baltimore's resistance toward banning alcohol.

Wedged between two sets of row houses is an awkwardly located family graveyard.