The preservation of monumental heritage in seismic areas is a crucial challenge, as such structures, often characterized by intrinsic fragility and historic materials, are particularly vulnerable to seismic events. The Basilica of Santa Maria degli Angeli in Assisi, one of the most important monuments in Italy, after the seismic sequence of 2016-2017 showed a complex damage scenario, also due to previous events and other causes, such as foundation settlements and aging of materials, so that it has required strengthening interventions to ensure its structural safety and the preservation of its historical and architectural value. This study presents a numerical analysis of the structural response of the Basilica after the consolidation interventions. A finite element model (FEM) was developed, incorporating detailed geometrical features, material properties estimated by in situ tests, and the technical specifications of the adopted strengthening measures, such as the introduction of steel tie-rods, grouted rods inside the masonry, SRG composite strips and more standard masonry consolidation techniques. The analysis has been focused both on the whole structure and, in more detail, on the central core of the Basilica, constituted by the drum-dome system, by performing static and dynamic nonlinear analyses. The results show a significant improvement in the structural performance under seismic loads, with reduced damage patterns compared to the pre-intervention conditions. Finally, comparisons with the pre-intervention models also show significant changes in vibration frequencies and associated mode shapes, consistent with the results obtained by a continuous dynamic monitoring system installed on the structures since 2017.