Sections of the historic wall collapsed in November 2019 and since then the council has been working with Lewes District Council and Historic England on plans to rebuild the structure.
Local building firm, Cheesmur Contractors, has been appointed to carry out the reinstatement work, working alongside structural engineering specialists The Morton Partnership. Both organisations have extensive experience with ancient and historic structures.
Following approval of the project plans from Historic England, work commenced this week as contractors established a site compound in the Maltings car park and Peace Garden.
Cllr Nick Bennett, lead member for resources and climate change, said: “There have been significant challenges to deal with since the castle wall collapsed, and I am delighted to see work start on site.
“Our project team has worked closely with local contractors and specialists to ensure the rebuild meets the detailed requirements of Historic England and is in keeping with the nature and construction of the original historic structure.
“We are very grateful for the enthusiastic support the project has received from local residents, businesses and property owners. I would like to thank them all for their patience.”
It is hoped work to rebuild the wall will be completed by the end of year.