The National Museum of Natural History has the Hope Diamond, but the National Postal Museum has the envelope wrapping used to mail the gem to the Smithsonian—part of a collection that consists of more than 6 million stamps. Exhibits, underscoring the important part the mail has played in America's development, include horse-drawn mail coaches, railroad mail cars, airmail planes, and a collection of philatelic rarities. Learn about stamp collecting and tour Systems at Work, an exhibit that demonstrates how mail has gone from the mailbox to its destination for the past 200 years, featuring a high-def film highlighting amazing technologies. Mail Call shows the history of the military postal system from the Revolutionary War to today, including a video entitled Missing You—Letters from Wartime. The William Gross Stamp Gallery, the largest of its kind in the world, has an additional 20,000 objects never before on public display, showing how closely stamps have intertwined
with American history. On display through February 16, 2016, Freedom Just Around the Corner: Black America from Civil War to Civil Rights is a chronicle of the African American experience told from the perspective of mail and stamps. Included in the exhibit are letters carried by enslaved Americans, mail to and from famous leaders of the civil rights movement and an extensive selection of original artwork for the USPS Black Heritage Stamp series from the Postmaster General's Collection. The museum is housed in the old Washington City Post Office, designed by Daniel Burnham and completed in 1914. Nostalgic odes to the noble mail carrier are inscribed on the exterior of the marble building; one of them, The Letter, eulogizes the "Messenger of sympathy and love / Servant of parted friends / Consoler of the lonely / Bond of the scattered family / Enlarger of the common life."