Rochdale Council has appointed Sir Robert McAlpine for the design and build of its new municipal office building in the town centre.
The new building will be home to 2,000 council staff and extend to between 250,000 sq ft and 320,000 sq ft in gross floor area.
The development will also feature a new library and information centre, public customer services, training and conference facilities together with offices for the NHS. The current municipal offices, dubbed the Black Box locally, will be demolished together with an adjacent bus station to make way for the £100m-plus retail and leisure development.
John Patterson, executive director at the council, said: "This is a really exciting step forward. Both of these companies have excellent reputations and we're already working with them to ensure we stay on track to deliver what promises to be a great building that serves Rochdale people and council staff for years to come."
A two-acre riverside site on Smith Street has been set aside for the new office, which will be close to a planned Metrolink stop.
Building work is due to start in early 2011, once VHE Construction has completed remediation of the site, which will get underway in the next few weeks. The building is expected to open in autumn 2012.
Newcastle-based architect Faulkner Browns won the contest to design the new council offices.
Sir Robert McAlpine is now liaising with the council's design team on the external design of the building, which the public gave their views on last September. The final design will be unveiled this summer.
Local suppliers will have the opportunity to find out what contracts are available in relation to the development of the building, at a special event at Rochdale Town Hall on 15 July.
Last October, Curtins Consulting was awarded with a structural engineering contract and the Manchester office of the RPS Group, located in Princess Street, gained a mechanical and electrical engineer contract for the development of the council's new municipal offices.