While its urban grain has remained the same for centuries, the architecture of Clerkenwell is in a state of constant, iterative change, as existing buildings are re-invented for new uses and newer structures inserted into gaps. This office building was originally built in the 1980s, but was up for demolition due to its poor condition. However, it had good bones: the floor-to-ceiling heights were generous, and the position of the core sensible, so we proposed a retrofit, rejacketing the building and adding two floors above the prevailing cornice height.