A diminutive plaque recalls the treetop sniper who almost killed Abe Lincoln.

This unassuming passageway played a key role in one of the most important events in U.S. history.

An ear-piercing buzzer calls lawmakers to a vote with a series of long and short rings to form coded messages.

A benevolent, 16-foot-tall river dragon lives on a suburban lawn.

A fantastic array of trays and cables once whisked books over to the Capitol at 600 feet per minute.

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

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

A historic cemetery with unique artwork, a Civil War fort, and also happens to be the site of the Battle of Bladensburg.

The legendary building that needed ghostly approval before being built.

Once the supplier for noteworthy projects like the National Cathedral, this old brickworks now lies abandoned.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

The span is crooked and made from two older recycled bridges.

Also known as the Founding Church of Scientology.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

Sit where JFK proposed to Jackie or where Nixon dined on meatloaf at this storied pub.

They sort through millions of dollars worth of diplomatic gifts on behalf of the government.

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

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

This robust fence in front of a historic Georgetown home is likely made from hundreds of recycled Revolutionary War firearms.

The first presidential bomb shelter was located in an old vault under the Treasury, connected to the White House via tunnel.

In the basement of the U.S. Capitol Building is a hidden storage room full of ornate floor tiles leftover from the 1850s.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.