The Johnson Building was AHMM’s first large-scale reinvention project. In knitting old with new in Hatton Garden, the scheme stands as an alternative to the temptation to start from a tabula rasa. The back half of a 1930s building (previously butchered by bombing and badly reconfigured post-war and then again in the 1980s) is removed and floors and cores stripped out to clean up the piecemeal plan. Behind, six floors of new office space are inserted, set back from the seven-storey found building with a dramatically tapered form to avoid loss of daylight to neighbouring buildings. A new, extended threshold cuts underneath and through the existing façade to lead into a new, full-height city room where bridges of precast concrete and glass lenses connect offices on both sides and bring animation and activity throughout. As well as being a model for delivery on a tightly constrained site, the building has set new standards in the speculative office market in terms of quality and cost. AHMM revisited the Johnson Building in 2017, refurbishing 4 lower floors of office space including the central atrium space and publicly accessible café. The office units have been reconfigured, removing parts of the ground floor slab and extending the floorplate in areas, interconnecting spaces via new steel staircases. Each unit has been provided with a corresponding new reception entrance, with the courtyard entrance from St Cross Street repaved to provide an enhanced approach. This new office space is accompanied by the 14 apartments and 10,000 square feet of jewellery workshops contained within Sweeps.