The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

People escaping slavery may have hidden inside a corpse vault.

Decades before the scandal, this staircase on the river was a literal "water gate."

You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

Art deco landmark on the outskirts of Washington, D.C.

The most accurate timepiece in the world.

A historic ruin just 20 feet away from a busy highway onramp.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

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.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

The walls of the iconic dome are hollow and have a secret stairway.

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

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

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

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

The site of the climactic scene from the classic horror film is now a historic landmark.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

The United States Capitol's former columns still stand.

A wonderfully strange collection of 500+ stuffed frogs doing people things.

An ancient knight and a symbol of the city's freedom.