The assessment and evaluation of historical masonry structures represent a well-known problem in the field of seismic engineering. Indeed, their unique value, often associated with a lack of documentation, represents also a constraint in the testing and evaluation of their geometrical and mechanical characteristics. Among them, bell towers represent a compelling category with inherent complexity, due to their slenderness and to the presence of elements such as large opening and adjacent buildings. In this context, appropriate models to simulate structural behavior play a fundamental role, especially in the definition of proper materials characteristics. The complexity in the behavior of these structures is often related to nonlinearity in material and geometric irregularity, requiring advanced computational tools.