Tea with Mussolini Movie.

Friends have asked whether the scenes where the English and American ladies save the towers from being blown up by the departing Nazis in WW 2 is based on any truth? And did the ladies actually work at saving the fresco of Santa Fina? Were they really held in custody in San Gimignano? I cannot find any WW2 history of the town to give me information on this. Please someone send me an email with the information. Information much appreciated! :)