Troia cathedral, Italy, is a three-nave, Latin-cross building, belonging to the Apulian Romanesque architecture. The naves, the chancel and the left transept were built, at different stages, approximately during a hundred years, starting from the end of the 11th century. The building has a maximum length of about 54 m, a maximum width of about 40 m, and a maximum height of about 33 m. The walls are made of limestone ashlar masonry, with the only exceptions of the bell gable and of limited raised sections of the transept, made of fired-clay-brick masonry. The central nave is covered by visible timber king-post trusses, while all other spaces present vaults below the roof. In 1731 a VII-VIII MCS earthquake caused extensive damage, including the collapse of the left transept, rebuilt immediately after, while the right one is a few decades more recent. The code seismic hazard of the site is moderate, with a 475-year-return-period-earthquake peak acceleration on rock of about 0.14 g. A 3D numerical finite-element model is implemented in FEAP, adopting a nonlocal scalar damage model to assess the earthquake vulnerability of the building. Although data from experimental investigations on the masonry are currently not available, and the geometry of the bell gable is still provisional (pending access to these spaces), preliminary assumptions allow for modal and pushover analyses, highlighting some weak points in the building performance.