This coming Sunday is a national Journée du Patrimoine throughout France with a theme this year of water and mills. there are events going on all over which you can search on their web site here is more info.
A couple of events which look interesting in the Vaucluse are a guided tour of the Gorge de Veroncle near Gordes. Another one focused on the Rue des Teinturiers in Avignon and another one covering the history of the Canal de Carpentras.