Work on a planned £30million redevelopment of Aberdeen Art Gallery could begin as early as next year.
The city council has issued a contract notice for the restoration project, which will transform the historic venue.
Interested companies have been asked to fill out a questionnaire, and a short-list of contractors will then be drawn up.
The plans include constructing a modern copper-clad extension on the roof of the Schoolhill building and removing the marble staircase inside, replacing it with a new staircase connecting all three floors.
The existing gallery roofs, a rear extension and a 1970s office block will be demolished – while a new addition to the north of the existing building will also be built to house education and support areas.
The War Memorial balcony will also be extended.
More of the city’s collection would also be made accessible to the public for the first time – as the exhibition space will be increased.
The city’s Labour-led administration has committed £10million towards the cost of redeveloping the Art Gallery, Cowdray Hall and Memorial Court, as well as £3million for a museums collection centre.
It is expected that a further £10 million will come from the Heritage Lottery Fund (HLF).
The project suffered a setback earlier this year, after a bid for £2million in funding from Creative Scotland’s Large Capital Fund failed.
However, the local authority has agreed to underwrite a further £10million for the project.
A council spokeswoman said: “A pre-qualification questionnaire has been published in order to select a short-list of principal contractors who will be invited to tender for the project.
“The Invitation to Tender documents are due to be issued in November, with a deadline for tender returns in January 2015, with a view to works beginning in the early part of 2015.”
Councillors voted by 27-15 in favour of the major facelift of the A-listed building in December last year.
The proposal had earlier been rejected by the authority’s planning development management committee, with members branding the design “corporate vandalism”.