The St George Hospital Stage 2 Redevelopment involved the construction of a new seven- level Acute Services building on top of an existing operational 24-hour Emergency Department.   The facility includes a 52-bed intensive care unit, eight operating theatres, sterile services department, 128-bed inpatient facility and rooftop helipad. The works also included a new substation, refurbishment of nine departments within the existing building, new main entrance and carpark expansion.  Major challenges for the project included working on an existing hospital site and building directly over the existing Emergency Department while constructing a new multi-level building above it.  Construction access had to ensure full ambulance access from Gray Street was available at all times. Materials handling was by way of tower crane, concrete boom pump and hoist.  Key difficulties that were overcome include the demolition and waterproofing of the roofing to the existing emergency area. A quiet, dust-free area was critical at this time. The maintenance of existing services was also critical to the emergency area, together with the remaining hospital. Late design changes were also incorporated into the program. The degree of difficulty for this project would be high given the direct interaction with the Emergency Department initially and then at each level where a link to the existing building has been established, together with the maintenance of existing services throughout the project.  The specified quality of the finishes was very high, with the overall level of finishes being raised to provide a more modern and up-to-date feel. The execution of theses finishes has been well done, with the overall feeling of this project to be of a high standard.  Multiplex has dealt with many complexities on this project in order to produce a well-finished hospital for Health Infrastructure NSW.