In 1676 the Prato nobleman Marco di Emilio Roncioni left in his will a sum of money to be used for creating a public library. The library was actually established, however, only in 1722, when the first books were purchased. Between 1751 and 1756 the building it still occupies was constructed. Administered and directed by a cathedral canon, it is one of the libraries that have been formed not around an old repertory, but with predominantly social objectives, in keeping with the philanthropic spirit typical of 18th century culture. Enlarged in the following years by various acquisitions, it boasts today a collection of Latin codexes and an interesting group of modern manuscripts, rich in local historical recollections. In the vast reading room, visitors can admire two world maps by Mercatore (Gerard Kremer), the reformer of scientific cartography in the 16th century. The library also possesses a small archaeological collection. Cultural and scientific conferences are frequently held in its elegant building.