The flag of Gibraltar is an elongated banner of arms based on the coat of arms of Gibraltar, granted by Royal Warrant from Queen Isabella I of Castile on 10 July 1502.
The flag was regularized in 1982 and is formed by two horizontal bands of white (top, double width) and red with a three-towered red castle in the center of the white band; hanging from the castle gate is a gold key centered in the red band. The flag differs from that of other British overseas territories, in that it is not a British ensign nor does it feature the Union Jack in any form. The castle does not resemble any in Gibraltar but is supposed to represent the fortress of Gibraltar. The key is said to symbolize the fortress' significance as Gibraltar was seen to be the key to Spain by the Moors and Spanish and later as the key to the Mediterranean by the British.