by Franz Steiner and Eric Elsesser (edited by Dorit Fromm). This booklet explains and illustrates the award-winning renovation and structural upgrading of Oakland City Hall, which had been severely damaged in the 1989 Loma Prieta earthquake. The decision to install a base isolation system as the most cost-effective solution was reached after eight alternative repair systems were compared and analyzed. The first high-rise building in California to be base isolated, it served as a model for designers and resulted in the acceptance of base isolation as a cost beneficial method of seismic risk reduction for historic buildings. It led the way for funding for other seismically isolated public buildings damaged by the Loma Prieta earthquake. This project introduced many new innovations, including the first walk-on moat that was part of the sidewalk, making it