The preservation of architectural heritage from natural hazards and catastrophic events, including the seismic risk, requires in-depth investigation on structural behavior and in particular on the dynamic response of monumental and existing buildings, such as masonry structures. The support of experimental tests, dynamic identification techniques together with structural monitoring allow to a non-destructive evaluation of dynamic parameters and more in general for the seismic vulnerability assessment of heritage buildings, preserving its integrity and considering its operational status. In this paper, an experimental campaign on unreinforced masonry (URM) walls is presented on three typologies of walls considering induced damage. A methodology for the investigation of dynamic behavior of damaged URM walls proposed to support the most common dynamic identification techniques pointing out information through a simple spectral estimation.