It is well known that the mine legacy is a serious concern to present communities. The high risk associated with subsurface voids together with the lack of knowledge of geometric and geomechanical features of former mining areas make abandoned underground mines one of the current challenges for countries with a long mining history. In Italy, no long-term assessment of abandoned mine sites is required by law. In this paper we deal with the case study of Montevecchia mine, a marl mine in northern Italy abandoned in 1958 after a massive collapse. The event affected all mine levels along their middle sections and caused a large sinkhole. We initially performed geological and geophysical investigations to develop a physical model of the site. After that we carried out several numerical simulations to evaluate the stability of tunnels still in place.