The museum holds 3 million artifacts including the U.S. flag that inspired Francis Scott Key to write "The Star-Spangled Banner."
A 2002 blue ribbon commission said the National Museum, the third-busiest of the Smithsonian museums, is unorganized and lacks space, The Washington Post reports.
The 42-year-old building on the Mall in Washington, D.C., will undergo $85 million of work before reopening in the summer of 2008.
A new gallery will be created for the flag that flew at Fort McHenry during the 1814 attack by the British, and a new welcome center will help direct patrons to various sites.
Notable deaths of 2014 [PHOTOS]