Bytom (Polish pronunciation: ; Silesian: Bytōm, Bytōń, ) is a city in Upper Silesia, in southern Poland. Located in the Silesian Voivodeship of Poland, the city is 7 km northwest of Katowice, the regional capital. It is one of the oldest cities in the Upper Silesia, and the former seat of the Piast dukes of the Duchy of Bytom. Until 1532, it was in the hands of the Piast dynasty, then it belonged to the Hohenzollern dynasty. After 1623 it was a state country in the hands of the Donnersmarck family. From 1742 to 1945 the town was within the borders of Prussia and Germany, and played an important role as an economic and administrative centre of the local industrial region. Until the outbreak of World War II, it was the main centre of national, social, cultural and publishing organisations fighting to preserve Polish identity in Upper Silesia. In the interbellum and during World War II, local Poles and Jews faced persecution by Germany. After the war, decades of the Polish People's Republic were characterized by a constant emphasis on the development of heavy industry, which deeply polluted and degraded Bytom. After 1989, the city experienced a socio-economic decline. The population has also been rapidly declining since 1999. However, it is an important place in the cultural, entertainment, and industrial map of the region. Geology The bedrock of the Upland of Miechowice consists primarily of sandstones and slates. The rocks are punctuated with abundant natural resources of coal and iron ore from the Carboniferous period. In the north part of the upland, in the Bytom basin lays the broad range of the triassic rocks, from sandstones to limestones, with rich ore, zinc and lead reserves. The upper layer is composed of clay, sand and gravel. Coat of arms One half of the coat of arms of Bytom depicts a miner mining coal, while the other half presents a yellow eagle on the blue field – the symbol of Upper Silesia. History Bytom is one of the oldest cities of Upper Silesia, originally recorded as Bitom in 1136, when it was part of the Medieval Kingdom of Poland. Archaeological discoveries have shown that there was a fortified settlement (a gród) here, probably founded by the Polish King Bolesław I the Brave in the early 11th century. After the fragmentation of Poland in 1138, Bytom became part of the Seniorate Province, as