NEWARK Castle is to undergo urgent repair work costing £175,000.
Small pieces of stone have been falling from the castle and a recent structural survey found it was suffering from erosion.
Part of the 12th century building has been fenced off to protect people from falling masonry.
Newark and Sherwood District Council, who are responsible for the upkeep of the building, has allocated £130,000 towards the repairs.
The remaining £45,000 will come from a heritage grant.
The survey also found that the castle will require future repair work costing more than £500,000 over the next five years.
The council carried out extensive work to restore the castle between 1979 and 1994 at a total cost of more than £1 million.
Most of this money came from English Heritage, but it has warned it would not be able to guarantee a grant due to Government cuts.
The historic castle was partly destroyed during the English Civil War, though many parts of the original Norman structure have survived.