Barnet, officially founded in 1965, is one of the largest London boroughs and is located in North London. However this borough started its growth in the 12th century. The well known Chipping Barnet market started here as early as 1199, but the famous Barnet fair began much later in 1588. Barnet fair is interestingly where the cockney slang for "hair" originated. Hendon Aerodrome is an important historical centre in this area. It was here that fighter planes were mass produced for the First World War, and also the world's first parachute jump from an aircraft originated here.