 The National Philatelic Collection contains nearly 
six million items and approximately 4,000 specimens from the collection are on public display in the National Stamp Salon of the National Postal Museum.It is among the largest and most valuable stamp collections in the world and – according to the Smithsonian Institution – is the "largest continuously intact museum collection" on Earth.It is also the second largest collection of artifacts held by the Smithsonian Institution, after that of the National Museum of Natural History.