Linked from
The 22 pages that link to Central bank, each with the reason it gives.
Federal ReserveNarrower topic: The Federal Reserve is the central bank of the United States.
Payment SystemRelated: Central banks commonly provide the settlement asset for interbank payments.
MoneyRelated: Central banks issue cash and shape the institutions supporting national money.
BanknoteRelated: Central banks commonly issue banknotes and control their supply.