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

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

This apartment building designed by a notable Washington D.C. architect housed the Qing Dynasty's Legation.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

A brass and marble scale model of the solar system embedded in the concrete.

A diminutive memorial marks the site of a successful assassination by a right-wing death squad in America's capital.

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

Before founding the American Red Cross, Clara Barton had a tremendous humanitarian impact by locating thousands of missing soldiers.

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

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.

Railroad officials in the early 1900s sought to spare travelers the sight of Roman soldiers’ private parts.

One of 100 “Whaling Wall" murals painted in 13 different countries by a renowned marine life artist.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

The first American department store, and home to the largest operating musical instrument in the world.

This elaborate towering structure was once famed for its revolutionary height.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

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

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

A much-maligned monument to teetotalism.