How the USS Constitution became an official historical site
Nicole E.
The U.S.S. Constitution was made
into an official historical site in 1976. It is now located in Charleston,
Massachusetts. Today only ten percent of the original ship exists. The
live oak forms the backbone of the ship that keeps it together and helps
repair and rebuild her. In 1925 she was fixed up and restored by school
children and patriotic groups. 
Also in 1925 congress commanded restoration of the constitution and a campaign was begun to raise money by public donations. From 1909 to 1925 "Old Ironsides" was used as a Naval museum and anchored in the Boston Navy yard. The U.S.S. Constitution is now the oldest U.S. warship still in commission. Between 1931 and 1934 "Old Ironsides" returned to her place of honor in the Boston harbor. In 1934 she was moored at a pier accessible to visitors. In August of 1940, her commission was restored and became a flagship for commandments of the first naval district.
Bibliography
http://www.geocites.com/CapitolHill/9703/history/constitution.html