Located on a rapidly expanding edge of Boston’s Financial District, this three-story addition on top of an existing six-story office building includes a new entrance lobby and new elevator core. The glass enclosing the new vertical elevator core is repeated at the ninth floor mansard to architecturally tie the main building to the new vertical facade. An intricate component of this addition, which proceeded without tenants vacating any floor of the building, was the introduction of an elaborate steel earthquake bracing system that extends the full height of the existing building. These mammoth steel braces required the construction of massive new foundations within the existing basement. Renovations also included reconstruction of the original cast iron storefronts at the street level facade.