Instituted by a decree of Grand Duke Leopold II on November 17, 1858, the Siena State Archives contain precious documents, noteworthy among which are three repertories: the Amendments (or Governmental Archives), the Contracts (or Notarial Archives) and the Diplomatic Archives. Since 1864 the Siena Archives have conserved the "tavolette" of the Biccherna (the medieval name of Siena's municipal tax office), of the Chamber and the Office, as well those as those of the Registers; these are ancient pictorial compositions used as covers of the codexes of the Biccherna and other magistratures in the Siena medieval commune. The Siena State Archives were later enriched by family archives donated or loaned by private citizens, and by the records of religious associations. Interesting from the scientific viewpoint are the records of the hospitals in the province, most notably those of Santa Maria della Scala, whose first documents, kept in the Diplomatic Archives, date from the 12th century, and the Prefecture records on the Department of the Ombrone pertinent to the administration of public works and the draining of the Maremma swamplands. Worthy of mention is the Ancient Sienese Measures repertory, with a collection of 60 pieces including measures of capacity, weights for scales and counterpoise weights of lever scales used in Siena in grand-ducal times and during the period of French government. Among the private records, particularly interesting are the Policarpo Bandini papers, with documentation (1790-1875) on the Sienese entrepreneur's connection with the Tuscan railways (Bandini was director of the construction of the Central Tuscany Rail Road), and the papers of Cesare Nerazzini (19th century-1924), official physician of the Navy who in his travels in Africa and the Far East gathered written and photographic documentation on the populations with which he came in contact, reporting on their customs and their diseases.