The date, almost two years behind schedule, will mark the completion of a redevelopment project which has brought the most significant investment since it first opened in 1885.

The revamp, which McLaughlin and Harvey began back in 2015, was initially scheduled to be completed in late 2017 at a cost of £30 million. Completion was then put back by at least a year.

Costs have also increased to £34.6m.

A key element of the council’s City Centre Masterplan, the project is transforming the Art Gallery, Cowdray Hall and Remembrance Hall into a major cultural attraction which is expected to attract around 250,000 visits annually.

Since work began in 2015, the Schoolhill complex of buildings has been completely reimagined and transformed by Hoskins Architects and exhibition designers Studioarc to meet both the needs of visitors and requirements for the care of the nationally recognised art collection.

The project includes investment in the fabric of the buildings, new exhibition and display galleries, improved visitor facilities and an enhanced activity programme.

Councillor Jenny Laing, co-leader of Aberdeen City Council, said: “The landmark redevelopment of Aberdeen Art Gallery, Cowdray Hall and Remembrance Hall is creating an exceptional centre for art and music in the heart of the city. It is part of an incredible period of positive change in Aberdeen, with the recent opening of the refurbished Music Hall and the excitement building as we prepare for the launch of P&J Live in the months ahead. With work on the restoration of Provost Skene’s House set to begin and Union Terrace Gardens ready to be transformed, it is a hugely important period in the story of Aberdeen.”

Fellow co-leader Councillor Douglas Lumsden added: “Aberdeen Art Gallery is a jewel in the city’s crown and the restoration and expansion is creating a world class attraction. It is an important part of the City Centre Masterplan and also supports our Regional Economic Strategy’s aim of diversifying the economy, building our reputation as a destination city. The cultural offering in Aberdeen has changed beyond all recognition in recent years and this project is of huge significance not only regionally but also in terms of our national and international standing.”

The project has received £10m from the National Lottery Heritage Fund and £14.6m from Aberdeen City Council’s Non-Housing Capital Fund. The fundraising campaign to secure the remaining £10m has raised £4.8m to date.