The USS Somerset moved up the Delaware River on Friday. It's christened for the Pennsylvania county where a hijacked airliner crashed after passengers stormed the cockpit.
The amphibious transport dock is the last of three vessels honoring 9/11 victims and first responders. It joins the USS New York and the USS Arlington.
The USS Somerset will be open for public tours beginning next week. The private commissioning ceremony, which officially places a ship into service, is scheduled for March 1.
The $1.2 billion vessel will then head to its home port in San Diego. It's designed to launch helicopters, tilt-rotor aircraft and assault watercraft.