This historic building was initially built in 1916 with an extension carried out to the rear of the building in 1933.  This project consists of the design and construction of a new 20 storey office building with the high rise floors (levels 10 to 20 roof) designed of steel framed construction with concrete slabs cantilevering over the historic buildings together with the restoration of the historic buildings. The design also re-established the light-well through a new atrium skylight spanning from the Banking Chamber to the under croft of the cantilevered structure. The conservation of the historic 1916 and 1933 building was one of the fundamental environmental objectives. The whole façade structure and the significant spaces and internal finishes were conserved. The trachyte recovered from the 1968 addition was re-used to clad the façade of the new extension.  The top 10 levels of the new 20 storey office building cantilevers 15-23 metres over the 1933 building, preserving the structural integrity of the original building and providing new floor plates with minimal core requirements and expansive column free floor space. This was achieved by the whole project team involvement in developing this innovative cantilever system with all of the building structure above the existing the 10th level of the  heritage building being supported using hanging columns on the western façade which formed an inverted King Post truss. The truss delivering the load of this section of the building to the northern and southern elevations and ultimately down to the foundations. This innovative cantilever tower was successful constructed without effecting the integrity of the original buildings by Grocon’s site team and their tradesmen demonstrating their exceptional skills and dedication to minute structural details demanded by the structural design.  The conservation of the heritage buildings and the new offices have been finished to an exceedingly high standard of workmanship with a magnificently restored Heritage Banking Chamber at its entry off Pitt Street.  The project is a credit to the whole design and construct team.