
May 1st, day of the worker, also known as "Primo Maggio". It is national holiday with local celebrations and rock concerts with popular international names.
Festa del Lavoro, not just celebrated in Tuscany but all over the Italy, "The day of the worker" is a national holiday. 1st of May, the banks, post offices, all public offices and many museums will be closed, many Museums are closed on Mondays anyway, bus and train system will still operate, bars and restaurants will all be operating normally and much life will go on as normal.
It is a public holiday all over Italy there is not much you can do about it. It is a perfect day to enjoy walking round Florence, take photographs or just to sit down in a good restaurant and have coffee and eat some good Tuscan food.