Final answer:
The oldest U.S. Navy ship still in commission is the USS Constitution, also known as "Old Ironsides."
Step-by-step explanation:
The oldest U.S. Navy ship still in commission is the USS Constitution, also known as "Old Ironsides." It is a frigate made from American oak and was first commissioned in 1794. The USS Constitution gained fame during the War of 1812 when it outran and out-sailed British ships. It is currently docked in Boston, Massachusetts, and is open to visitors.