O’Connor Sutton Cronin was appointed to do the Fitzwilliam development project. The main portion of the Project Fitzwilliam Development was split into two blocks over a common basement with No 27 Fitzwilliam (Block B) forming the New ESB Head Office and No 28 Fitzwilliam (Block A) a speculative office development. 

• 5-7 storey reinforced concrete structure over double, and part triple, level basement providing c.30,000m2 of office accommodation in the overall development of c.42,000m2 
• The development replaces the existing ESB offices on a brownfield, city center site with careful demolition of existing structures adjacent to existing protected structures. In addition, the piling works, excavations, and basement construction were undertaken abutting existing structures and also through existing basement structures.  
• The foundation structure to the northern portion of the site consists of a foundation slab bearing directly onto bedrock with the presence of the historical quarry to the south necessitating a piled foundation solution.  
• Fitzwilliam Street consists of a load-bearing brickwork frame to complement the setting of the development.