The site is to be redeveloped to include 151 new homes, a community centre and a new Aldi supermarket building.
Demolition of Ashdown House, which was formerly used by the Department of Work & Pensions (DWP) and other businesses, started in January last year and was completed by June.
Plans for the mixed use development scheme on land between Sedlescombe Road North and Harrow Lane were given the go-ahead by Hastings Borough Council in January 2022 and are due to be completed by the end of this year.
Developers said 17 of the 151 homes will be affordable rented housing provided by The Hyde Group. Plans for the new Aldi store were announced in September 2021 as part of the redevelopment, with up to 50 jobs are expected to be created as a result.
Work on the development suffered a set-back in early may when an explosive shell was discovered. Surrounding buildings were evacuated as The Ministry of Defence sent its explosive ordnance disposal team to safely detonated the 105mm (4.13in) shell. Work has carried on at a good pace since then.
The work is being carried out by Maidstone-based construction company, Chartway Group.
Have you read? Hastings more popular than Eastbourne as a survey rates it the fifth best seaside resort in the UK
Have you read? In pictures: Classic steam trains at Robertsbridge