The National Galleries of Scotland (NGS) said the new extension will radically improve access to its world-class collection of Scottish art. The Scottish rooms, Print Room and Library in the Lower Level of the Scottish National Gallery (SNG) closed this week to allow for the preparation of the building.

Michael Clarke, director of the SNG and project director, said: “We are delighted that we can now move forward with this exciting development. I would like to thank the City of Edinburgh Council for their support of this project which will truly transform this site at the heart of Edinburgh and enable new audiences to enjoy the magnificent Scottish art collection.”

The planned redevelopment of the Scottish National Gallery, will triple the exhibition space available to the Scottish collection from 440 m to 1320 m, vastly improve visitor access and circulation throughout the SNG complex, and create a more sympathetic setting and entrance for the SNG within East Princes St Gardens.

Hoskins Architects was appointed to the project in 2014. Before his untimely death earlier this year, the firm’s founder Gareth Hoskins OBE created the design, which is being taken forward by the practice team, led by director Chris Coleman-Smith.

Designed by the celebrated Scottish architect William Henry Playfair (1790-1857) and situated right in the heart of Edinburgh, the SNG is the most popular UK art gallery outside of London, attracting over 1.4 million visitors in 2015/16.

The Heritage Lottery Fund announced a £4.94m grant towards the project earlier this year.

Actual construction work will commence on site in spring 2017 and will continue until autumn 2018. The new spaces will open to the public in early 2019.

During the renovation, the SNG will remain open to the public with access to rooms at the ground and upper levels.