The Temple of Diana in Baiae exemplifies ancient masonry dome construction, with a unique ogival profile partially built in opus caementicium. This paper investigates its structural vulnerabilities using two analytical approaches: Thrust Network Analysis (TNA) and Finite Element Methods (FEM). While TNA is efficient for structures with distinct masonry blocks, it struggles with Roman concrete’s continuous casting. FEM, effective for continuous systems, is influenced by boundary conditions like settlements. A comparative analysis highlights the strengths and limitations of both methods, emphasizing their complementary roles in structural assessment.