Caio Duilio (C 554) was an Andrea Doria-class helicopter cruiser of the Marina Militare.

Built by Navalmeccanica at Castellammare di Stabia, it was named after the Roman consul Gaius Duilius.

The Andrea Doria class was intended to provide long range anti-aircraft and anti submarine protection, and as such was armed with a single Mark 10 twin rail launcher for the American Terrier surface-to-air missile forward and a large helicopter deck and hangar at the aft end of the ship.

[1][4] Close-in anti-aircraft protection was provided by eight 76mm/L62 Allargato rapid fire guns mounted on pedestals around the ship's superstructure, while two sets of triple torpedo tubes for lightweight anti-submarine torpedoes provided short range anti-submarine armament.

The ship's original hangar was turned into classrooms and additional accommodation, with a new, smaller, hangar being built on the forward part on the helicopter deck, reducing the ship's aviation capacity to two helicopters.