Studio Weave has transformed an awkward exterior space landlocked by buildings into the Lullaby Factory – a secret world that cannot be seen except from inside the hospital and cannot be heard by the naked ear, only by tuning in to its radio frequency or from a few special listening pipes. Due to the phasing of the Great Ormond Street Hospital redevelopment, the recently completed Morgan Stanley Clinical Building has been designed to overlook a landscape that will not be in place for 15 years. In the intervening period, large windows in the west elevation look directly on to the 'back' of the 1930s Southwood Building, with the gap between the two less than one metre in places. In our competition entry we proposed that the Southwood Building, with its oodles of mysterious pipes and plant, is not really the Southwood Building, but the Lullaby Factory: manufacturing and releasing gentle, beautiful lullabies to create a calming and uplifting environment the young patients to recover in. Our aim for this project was to re-imagine the Southwood façade as the best version of itself, accepting and celebrating its qualities and oddities; and rather than hiding what is difficult, creating something unique and site-specific. We have designed a fantasy landscape reaching ten storeys in height and 32 metres in length, which can engage the imagination of everyone, from patients and parents to staff, by providing an interesting and curious world to peer out onto. Our design is mindful of the fact that the space between the two buildings is very tight and any attempt to tidy it up too much would have resulted in significantly reducing the sense of space and the amount of daylight reaching inside the surrounding buildings. Aesthetically the Lullaby Factory has been inspired by a mix of an exciting and romantic vision of industry, and the highly crafted beauty and complexity of musical instruments. We hope the project will inspire engagement at Great Ormond Street Hospital in a variety of ways from children’s paintings to a resource for play specialists to a generator for future commissions.