In Defense News, Rear Admiral Vic Guillory writes:
The U.S. Navy has 22 Ticonderoga-class Aegis guided missile cruisers (CGs). Commissioned in 1986, Bunker Hill is the oldest and has the distinction of being the first to receive the full hull, mechanical and electrical, and combat systems “cruiser modernization” overhaul. This capability-enhancing, life-extending modernization program provides the most up-to-date warship at a fraction of the cost of new construction.
Upgrades include new computers, Block 1B Phalanx CIWS, Evolved Sea Sparrow missiles, and new 5 inch/62 cal guns to replace the original 5 inch/54 cal guns.
Read the whole article for more details on the upgrades.