The archives of the former Italian State of Lucca are sited in Piazza Guidiccioni, Lucca. Tehy are one of the most important of the Italian archives, partly because of the method of organisation used. They were created under state legislation of 27 August 1804.
More information on the Italian Wikipedia page [1]
The website, under construction (May 2014, December 2015), is to be found here [2].