Many archaeological sites in the world are threatened by natural hazards, so that, susceptibility analysis is essential for reducing impacts and sustain site fruition by visitors. In this paper, the analysis of the susceptibility to rockfall of the western slope of the Cumae Mount in the Cumae Archaeological site (Phlegraean Fields, Naples), already affected by rockfall events, is presented with the aim of supporting a management plan in site conservation and fruition perspective. Being the first Greek settlement of southern Italy, the site has great historical importance and offers unique historical elements like the Cumaean Sibyl’s cave. The analysis began with a 3D reconstruction of the slope by means of digital terrestrial photogrammetry, which forms a basis for a geomechanical analysis. Digital discontinuity measurements and cluster analysis provides data for kinematic analysis that underlined planar, wedge and toppling failure potential. Subsequently, a propagation-based susceptibility analysis was completed into a GIS environment, indicating that most of the western sector of the site is susceptible to rockfall including the access road and a segment of the Cumana railroad, including the local station. The work underlines the need for specific mitigation measurement and the effectiveness of filed-based digital reconstruction in supporting susceptibility analysis in rockfall prone areas.