Inside the State Archives, in the magnificent Piccolomini Palace, there is a museum that is really unique, the one holding more than one hundred Biccherna Tablets.
The Biccherna (word of uncertain origin, perhaps coming from the Blacherne of Constantinople, where the imperial treasure was kept) was the most important financial magistrature of the Municipality of Siena and, since the middle of the thirteenth century, they made the best Sienese painters paint the covers of the administration registers on wood tablets. The custom was also adopted by other city institutions and it made it so that today we have an exceptional collection of artworks signed by Sano di Pietro, Giovanni di Paolo, Lorenzo Vecchietta and many others.
At the end of the fifteenth century, Biccherna and Gabella decided not to have the tablets painted anymore, but actual paintings - some of which are preserved in the Museum itself – a custom interrupted only in the eighteenth century.
Also, exhibited here is the Costituto of 1309, a sort of “constitution” of the Municipality of Siena which had - for the first time in "vulgar italian" and not in Latin - the set of norms and laws that governed the public life, so as to make them understandable to a wider audience.