Roger Cornwell, chairman of the City of Durham Trust, has not given up hope of a return of the missing bust of the head of structural engineer Sir Ove Arup.
The bronze sculpture was taken from its concrete plinth outside Durham Students' Union building, Dunelm House, alongside the engineer's favourite structure, Kingsgate Bridge.
Arup designed and oversaw the building of the award-winning footbridge, over the River Wear, linking the Elvet area of Durham with the city's cathedral and castle peninsula, in 1963.
Although famed for his work on Sydney Opera House, The Barbican Centre and the Penguin Pool, at London Zoo, the Newcastle-born philosopher and engineer believed the bridge was his finest work.
Arup, the son of a Danish consul, died in 1988 at the age of 93.
The bust, designed by sculptor Diana Brandenburger, was unveiled by Arup's daughter, Karin Perry, on the 108th anniversary of his birth, in April 2003.
But it was reported missing overnight on June 12 this year, at a time work was under way building new disabled access to Dunelm House.
Mr Cornwell said: "Although it may have been taken to melt down, it might just have been taken as a keepsake or memento of Durham. We just want it back.
"We haven't thought about a replacement, that would be very costly."