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

The institution is sitting on a goldmine of 21,000 paints, varnishes, pigments, and primers preserved for posterity.

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

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

The sculptor was instructed to add “stallion attributes” to the general's bronze mare.

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

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

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

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

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

This statue of the "father of television" stands prominently in the United States Capitol.

The elevator that makes it possible to fly American flags in bulk over the U.S. Capitol

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

Senators used to relax in the nearly forgotten marble tubs now hidden in the U.S. Capitol Building's basement.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

The tunnel under the Capitol Building where Congress takes out its trash.

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

The first memorial dedicated solely to the Black troops who fought for the Union.

A haunting tribute to pioneering photographer Clover Adams.

A pre-Industrial Age iron furnace and the site of a nearly-forgotten piece of Black history.

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

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

This former asylum for Black Americans is haunted by its history of violence and racism.