The intervention prioritises the reuse of the existing structure, with minimal demolition limited to specific areas at the entrance and rear. These targeted operations enable the creation of double-height spaces, enhancing natural light and visual continuity, while significantly reducing construction waste. The library is articulated in two volumes around a central courtyard, connected through a compact circulation core. The new volumetry introduces a more prominent façade facing the square and lowers the rear to optimise solar exposure on adjacent streets. A thermodynamic façade captures energy, and two large skylights bring natural light into the entrance and multipurpose hall.