The APN's Boston-class were the first guided missile cruisers in the world. Both ships in this experimental class were originally Baltimore-class heavy cruisers that had been decommissioned after World War II, but were redesignated as guided missile heavy cruisers (CAGs) and entered refit in 1952. The lengthy conversion and modernization project involved removing the aft triple 8-inch gun turret and its supporting structure and installation of two twin launchers for Terrier anti-aircraft guided missiles. The forward two 8-inch gun turrets remained unchanged. The forward superstructure was modified to include the Terrier's associated radars and electronics, the aft superstructure was completely replaced, and Baltimore-class's two funnels were trunked to one.
Owing to the Boston-class's experimental nature, the ships were only partially converted, with a full conversion to be carried out if the new weapon systems were successful. Had the ships been fully converted, the forward 8-inch turrets would have been replaced with additional Terrier launchers.
Various proposals for limited modernization or complete reconstruction were considered but ultimately rejected. In 1970 both Boston-class ships were decommissioned for the final time, eventually struck from the Naval Vessel Register, and sold for scrap.
- Type: Guided Missile Heavy Cruiser (Hull designation symbol CAG)
- Service Period: 1955-1970
- Length: 673 feet 5 inches (205.26 meters)
- Beam: 70 feet 10 inches (21.59 meters)
- Height: 112 feet 10 inches (34.4 meters)
- Draft: 26 feet 10 inches (8.18 meters)
- Displacement: 16,240 tons (Standard); 19,040 tons (Full Load)
- Crew: 1,146 (61 officers and 1,085 sailors)
- Propulsion: Geared steam turbines with four screws
- Speed: 33 knots (61.12 km/h)
- 6 x 8"/55-caliber Mk.15 naval guns
- 10 x 5"/54-caliber Mk.16 dual purpose guns
- 8 x 3"/50-caliber Mk.22 anti-aircraft guns
- 2 x Mk.4 twin arm missile launchers (firing RIM-2 Terrier AAMs)
- APNS Boston (CAG-01)
- APNS Pittsburgh (CAG-02)