Bath Iron Works (BIW) is a major United States shipyard located on the Kennebec River in Bath, Maine, founded in 1884 as Bath Iron Works, Limited. BIW has built private, commercial, and military vessels, most of which have been ordered by the United States Navy. The shipyard has built and sometimes designed battleships, frigates, cruisers, and destroyers, including the Arleigh Burke class which are currently among the world's most advanced surface warships.
Since 1995, Bath Iron Works has been a subsidiary of General Dynamics. It is the fifth-largest defense contractor in the world as of 2008. During World War II, ships built at BIW were considered to be of superior toughness by sailors and Navy officials, giving rise to the phrase «Bath-built is best-built.»