Bluemantle and Kilmartin have been granted planning permission to refurbish the Grade 2-listed Miller Arcade in Preston.
The scheme will bring back into use over 30,000 sq ft of offices and three new leisure units. Miller Arcade, on the corner of Fishergate and Church Streets, facing the Town Hall, currently provides 50,000 sq ft of office and retail accommodation over five floors.
Bluemantle / Kilmartin acquired MiIller Arcade from Maple Grove for £8.6m earlier this year.
Mark Caldwell of Bluemantle said: "The new facilities that will be created will not only support Preston's existing retail and leisure business but will also help attract new companies to the area. By improving the Arcade's existing offer, we will be able to play our part in the continuing development of Preston city centre."
Work is due to start on site early 2009.