Yesterday (Thursday, May, 12) building control officers were alerted to possible movement in the Lewes Castle wall that overlooks Mount Cottages.
A specialist structural surveyor was asked to undertake an inspection of the wall and assess its condition.
A spokesperson at Lewes District Council, said|: "Their report confirms a risk that the wall is in danger of collapse and that neighbouring properties should be vacated while further assessments are carried out and mitigations considered.
"These are precautionary measures until we are satisfied that there is no risk to residents in the area.
The council is offering full support, including accommodation, to all those affected by these developments. We expect to be able to provide an update later today."
A spokesperson for Sussex Past stressed the castle was open to visit as normal.
He said: "The stretch is well away from the part we look after and is another part of the privately-owned section. The Castle as an attraction remains open and safe) for people to visit."
In November 2019 another privately-owned piece of the castle wall collapsed causing significant damage.
It fell into someone’s garden and against the Old Coach House.
The castle itself was not affected but was closed to the public for safety reasons.