In this context, a preliminary experimental campaign was conducted on 3-5 October 2017 to measure the ambient vibrations of the "Voltone", a large vaulted masonry structure located beneath "Piazza della Repubblica" in Livorno. Some accelerometers provided by the Dept. of Civil and Environmental Engineering of the University of Florence and some accelerometers developed in the MOSCARDO project by EIS S.r.l were installed on the intrados of the vault. Data recorded during the three-days experiments will allow the dynamic identification of the structure.