The district-free town of Kempten, surrounded by the district of Oberallgäu is independent from an administrative point of view. District-free towns are normally larger middle-sized and large towns with a population of over 100.000. Further district-free towns are, for example, also Rosenheim and Munich. Kempten is one of the oldest towns in Germany; the Roman town of Cambodunum existed after about 15 BC. The economic basis in the Middle Ages was the long-distance trade in salt, furthermore, linen cloth and blacksmith crafts were produced locally. With the decline of linen manufacture in the 19th century due to strong competition on the world market, land usage changed from growing flax to pasture farming and as a consequence cheese production developed. Nowadays the dairy industry is of international importance. With district reforms in 1972 the area of the town increased from 24km2 to 63km2.