The Historical Archives of Celje collect and and keep records of the archives of organisations and institutions of local and regional interest. Its remit includes the state administrative units (territorial divisions other than municipalities used in state governance): Brežice, Celje, Hrastnik, Krško, Laško, Mozirje, Sevnica, Slovenske Konjice, Šentjur, Šmarje pri Jelšah, Trbovlje, Velenje, Zagorje ob Savi and Žalec. It has a branch unit for the Posavje region. Although its origins date back to the activities of the 19th century Museum Society, the Historical Archives Celje was established in 1956. At the beginning it encompassed 11 municipalities, but since 1994 it has expanded to 30 municipalities. From 1961 to 2001 the archives were housed at the Protasi Mansion, but nowadays they are housed in new modern premises. Its holdings include archives dating from the 13th century to 1992, the vast majority of which were created after 1850 as unfortunately the holdings were damaged by war and subsequently by the floods of 1954. The registers hold some 6,500 linear metres of material on various fields, including government, jurisdiction, economy, education, medicine, associations and social organisations and a modest collection of old documents by landlords and guilds (specifically various 13th-century manuscripts). The Historical Archives of Celje has co-operated successfully with the Graz Regional Archive (Steiermaerkisches Landesarchiv Graz, Austria), the National Archives in Zagreb, Croatia and the Historical Archives in Pančevo, Serbia.