Knowles & Son (Oxford), based in Berinsfield, was established in 1797 and reached nearly £30m turnover, according to latest published results.
But staff were told last week that the firm had called in administrators from Duff & Phelps and their jobs had been axed.
Knowles worked predominantly within Oxford City and the surrounding counties.
The firm carried out building and restoration work for Oxford University, the National Trust, The Heritage Lottery Fund, and Oxford Preservation Trust.
It had been in the hands of the Knowles family for eight generations.
According to last accounts for 2016, Knowles had crept back into the black making a pretax profit of £600,000 after two years of losses of £1.3m and £1m respectively in 2015 and 2014.