sentences:  In 2011, three industry clusters were established – The Cluster of Polymers Manufacturing "Plastosfera", Częstochowa Communal Cluster "Aglomeracja" and the Regional Cluster of Building Industry and Infrastructure "Budosfera".Industry
  Częstochowa is the main city in the Częstochowa Industrial District, which is the third biggest in the Silesian Voivodship.Since the medieval times, the metal industry has been developing, thanks to the iron ore deposits.