Government funding of £1.2m has been secured to preserve Lindisfartne Castle for future generations.
The castle, on Holy Island, is deteriorating due to its exposure to salt, wind and sea.
The exposed location of the castle on the Northumberland coastline puts the fabric of the building under constant pressure from the elements.
As a result the building suffers from penetrating damp which in some areas puts the Castles contents at risk. There are also many leaking historic windows.
Lindisfarne Castle is a popular tourist destination, with nearly 100,000 visitors each year. Built in around 1550, it now has Grade 1 Listed status.
Work will begin this summer to trial conservation techniques for the castle, with a view to project work beginning in 2017.