Music performances frequently take place in ancient religious buildings and significant problems related to acoustic quality may occur. Measurements results obtained in 10 historically significant churches in the city of Genoa, Italy, are examined. Experimental data obtained from research literature on auditoria and chirches have been compared with the experimental results. A survey of the available theoretical models of the spatial distribution of the most significant acoustical parameters have been conducted and the most suitable model for religious buildings have been applied to the selected churches. A comparison between theoretical models and experimental data is presented. A case study on the effects of permanent and non permanent acoustical treatment, without significantly changing the architectural characteristics is presented for one of the analysed churches. The results of the measurements in various phases of the acoustic threatment and some software simulations are presented.