Following a consultation period with planning and heritage officials, work on converting the former National Health Service property began at the beginning of May.
A 12-week works schedule will transform the building - a Georgian town house with a large Victorian extension originally designed as meeting rooms for members of the Church of Scotland - into what Bonhams say will be state-of-the-art salerooms.
The 6500 square feet of public space will be finished in much the same way as Bonhams' New York offices: open-plan spaces employing polished limestone, glass and corian. With one large saleroom on the ground floor and two interlinked salerooms upstairs, there will be three selling spaces in total.
Miranda Grant, Bonhams' director of Scotland, told ATG: "I think people are going to be really surprised by the non-traditional space that we've created."
With items still being sourced for the inaugural auction, star of the sale so far is a sculpture by Robert Forrest (1789-1852) of James V - the last member of the royal family to hold only the title King of Scotland.
James V at Cramond Bridge, was carved from a single piece of sandstone and is believed to weigh more than 14 tonnes.
The statue depicts an event popularised by Sir Walter Scott in his Tales of a Grandfather, where James V was attacked while crossing the Cramond Bridge. Local tenant farmer Jock Howison rescued the king and was rewarded with the land around Braehead.
The sculpture is expected to fetch £30,000-50,000.
In the meantime Bonhams will continue to hold their Edinburgh sales at the Signet Library on Parliament Square, the next on July 15-17.
By Roland Arkell
