A £38.62m revamp has created 12 brand new galleries for Scottish art underneath the original 19th Century building on Edinburgh’s Mound.
But it is opening five years later than originally planned and has cost double the original price tag.
“It’s been a complex project,” admits Sir John Leighton, the director-general of the National Galleries of Scotland.
The original gallery devoted to Scottish art was created in the basement in 1978 but it quickly became clear that it could not accommodate the vastly expanded collection of more than 60,000 works.
And there was the additional problem of many artworks being too large to be moved down to the basement space – an issue which has been resolved with the new space’s vertical picture lift.
Visitors were not convinced about the original basement space either, with only one in six Scottish Gallery entrants making their way downstairs.
The original plan was to expand the gallery into the 70s office space alongside the basement, extending out into Princes Street Gardens, and five metres (16ft) over the railway line.
Planning permission was granted in August 2016 but having failed to reach agreement, the project had to be reworked and relaunched in 2018, when it was estimated to cost £22m.
The first phase was successfully completed in 2019 with a new entrance in Princes Street Gardens, a terrace and landscaping, and a café and shop.