The University Laboral of Gijón is an emblematic architectural complex located in Asturias, Spain. Built between 1946 and 1956, it stands as one of the prime examples of modernist architecture in the country. Its design integrates a unique combination of functionality and aesthetics, employing innovative materials for the time such as reinforced concrete, brick, and natural stone, and following a monumental composition noted for its symmetry and grandeur. Among its buildings, the theater is one of the most prominent structures, originally conceived as a premier cultural space. However, over time, the theater of the University Laboral of Gijón experienced significant deterioration, both structurally and functionally. As the building aged, acoustic problems became increasingly apparent, preventing the theater from adequately fulfilling its original purpose. The poor acoustic quality, characterized by excessive reverberation and uneven sound distribution, negatively affected the audience's auditory experience and the performers’ delivery. In light of this situation, a comprehensive intervention was proposed to restore and modernize the theater, aiming to resolve the acoustic issues and restore its utility as a cultural space. This intervention included the renovation of materials, the implementation of new acoustic technologies, and a reconfiguration of the interior space. However, despite the intentions, the results of the intervention were counterproductive. Far from improving, the acoustic quality of the theater significantly worsened, rendering it unusable as both a theater and an auditorium. Moreover, the theater lost part of its architectural identity due to the modifications. To address the shortcomings of the previous intervention, it became necessary to completely redesign the theater, altering its design, materials, volume, and more. This extensive modification risked stripping the theater of its architectural identity. The issues of reverberation and poor sound distribution were exacerbated, highlighting the need to completely rethink the intervention approach. In response to this failure, acoustic virtualization was employed as an innovative solution to revitalize the theater without compromising its valuable modernist architectural style. Acoustic virtualization allowed for the simulation and analysis of the space's acoustic properties using advanced digital techniques, enabling a more precise and respectful intervention that adhered to the theater's original design. This technology facilitated the identification of problematic areas and the implementation of solutions tailored to the specific characteristics of space. Thanks to acoustic virtualization, the sound quality was significantly improved while respecting the initial volume and design of the structure. The application of this technology not only resolved the acoustic problems but also maintained the aesthetic and architectural integrity of the University Laboral of Gijón theater. The results achieved after the intervention based on acoustic virtualization were satisfactory, restoring the theater's functionality and allowing its use as a multifunctional cultural space. Thus, the theater has regained its central role within the architectural complex, combining the preservation of historical heritage with contemporary acoustic quality needs.