The technical expertise developed for the seismic rehabilitation of a rigid building in Slatina, Romania—repurposed as a school—required implementation of base isolation, considering the known seismicity of the site. Based on structural and architectural analysis, the building, characterized by high stiffness in all directions, was modeled as a rigid body with elastic connections at the base. The structure consists of two monolithic reinforced concrete bodies: one measuring 35 m in length and 20 m in width with a ground floor and one upper level (P + 1), and another measuring 15 m × 20 m with a ground floor and three upper levels (P + 3). The building is symmetrical about the longitudinal median plane. Dimensional measurements and identification of materials allowed evaluation of volumes, gravimetric parameters, geometric configurations, and the symmetry conditions of structural and inertial stiffnesses. These confirmed compliance with Eurocode 8 symmetry provisions, validating the rigid body hypothesis. The feasibility of base isolation was assessed using a system of elastomeric devices manufactured in Romania, tested and certified per EN 15129 by ICECON CERT, a notified EU body. The isolation system consists of four support groups and two constructive types of devices, designed to achieve a natural frequency of 0.35 Hz for horizontal displacement. Seismic excitation at 0.5 Hz—specific to the building’s location—was considered. For excitation mode 1 from the spectral composition of the seismic action, equivalent modal damping and equivalent seismic damping relations were established. The study demonstrates the effectiveness of base isolation for ensuring seismic resilience and structural integrity in educational facilities.