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

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

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

This forgotten boat elevator was an engineering marvel in its heyday.

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

A historic arena where the Beatles played their first concert in the U.S.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

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

The most accurate timepiece in the world.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

The national park was once a plantation estate.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

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

A clone of a cloned tree that was so important it allegedly had its own guards.