Britain's Royal Armouries, which houses the nation's collection of arms and armour, has opened a permanent branch in the US.
This 16th Century helmet is among the Royal Armouries' exports
It has forged links with Louisville, Kentucky, famous as the birthplace of boxing champion Muhammad Ali.
Part of the new Frazier Historical Arms Museum is devoted to 300 items borrowed from collections in the UK.
The Royal Armouries has sites at Leeds, the Tower of London and at Fort Nelson near Portsmouth, Hampshire.
Alan Green, the chairman of the Royal Armouries, said: "Our relationship with the Frazier Museum offers a wonderful opportunity to share our historical links with the widest possible audience."
The items on display in Louisville present the military history of the British Isles from 1066 to the early 1900s.
The collaboration between the two museums also marks the launch of the American Friends of the Royal Armouries, a charitable offshoot created to attract new funds.