Dutch practice Mecanoo plans to revamp the B-listed hall to form a flexible museum, exhibition space and café to help meet the city’s cultural aspirations.

The firm was selected by a panel from Perth & Kinross Council last August following an international design competition which drew more than 70 initial expressions of interest from across the world.

The milestone Tay Cities Deal agreement, signed by council leaders last week, has cleared the way for the latest plan, which details how the transformation will be carried out.

Mecanoo’s proposals include two new entrances linked with an interior vennel space, a 70-cover licensed cafe, a three-story pavilion as part of the main hall and a second floor gallery.

The original entrance area will become a key part for the permanent gallery, with two grand staircases linking collections on the ground and first floors.

In a statement Mecanoo wrote: “The entrances will require the existing doorways in the stone external wall to be expanded and a new structure introduced. A metal clad surround will shelter and announce the entrances.

“The vennel leads to the centre of the hall where visitors will enter in the centre of the space under the vaulted ceiling and in front of the new pavilion. The first-floor gallery sweeps round the space encouraging people to explore the upper levels.”

The project is part of a planned £30 million overhaul of the city’s cultural assets, including a refurbishment of the Perth Museum and Art Gallery on George Street.

The public will now get a chance to have its say on the scheme before it goes before councillors for a final planning decision next year.

Council leader Murray Lyle said: “I am delighted that people in Perth and the surrounding area will see renewed vibrancy in the city centre, thanks to funding being confirmed for the redevelopment of Perth’s museum portfolio.

“The council’s commitment to investing in buildings which promote the cultural economy means the City Hall project is able to move forward immediately. It is a key element of the city’s ongoing cultural transformation, which will bring people into the city to enjoy food, music, art and heritage.

“Feedback from local residents and businesses is really important to help us shape this exciting project, and I hope that as many people as possible will take the time to share their views on the plans.”

BAM Construction will work with hub East Central Scotland to redevelop the Edwarian building, with construction expected to start work in 2019 and the grand opening scheduled for 2021.

The contractor will also lead the £10m Hoskins Architects-designed revamp of Perth Museum and Art Gallery with Ogilvie Construction tasked with building the new collection store on a separate site.

London-based design practice Metaphor has been appointed as the “interpretation and exhibition designers” for both venues and will work with the respective architects to develop new interiors and exhibition spaces and bring the stories of Perth’s Ancient Roots and its Modern Scots to life.