The paper investigates the effects of the construction of a 30 m deep excavation, supported by diaphragm walls, on the ancient masonry walls of the city of Rome, the Mura Aureliane at Porta Asinaria. A numerical approach is proposed to investigate the soil-structure interaction mechanisms and to assess the possible damage on the heritage structure. Advanced constitutive models are used to describe the mechanical behaviour of both the masonry structure and the soil: the former is schematised as an anisotropic medium, whose elastic response and yield criterion are derived via homogenisation, while the latter is described by a hardening plasticity-based soil model, capable of taking into account the dependence of the stiffness on the strain le...