For the case of urban overhead lines, the presence of nearby buildings is expected to affect the overvoltages induced by nearby cloud-to-ground lightning return strokes. So far, this effect has been seldom taken into account in the literature on the subject. The paper presents a 3D FEM model that calculates the lightning electromagnetic pulse (LEMP) taking into account the presence of a building placed in proximity of the LEMP-coupled overhead line. As a first approximation, all the metallic elements are assumed as perfect conductors, as well as the ground plane. The calculated fields are then introduced in the Agrawal et al. coupling model for the calculation of the induced voltages. The results of a sensitivity analysis carried by varying the model and dimensions of the building, its distance to the line and the position of the lightning stroke location are presented and discussed.