Edinburgh International Conference Centre is inviting bids for an £85 million contract to design and build additional function space.
The space is primarily an underground extension linked to the existing conference centre by an atrium building with a 17,500 sq m office block of approximately small retail element constructed above ground.
Contractors tendering for the job must have a minimum turnover of £200 million.
Up to five firms will be invited to tender for the 30 month on 17 August.
Pre-qualification questionnaires are due in by 24 July.