The Trustees of Berkeley Castle in Gloucestershire have decided to reduce the days on which the attraction will open to public in 2008.
According to a spokesperson, dwindling visitor numbers have lead to the site to making a loss of around £100,000 each year, forcing the attraction to look at ways to cut costs.
The decision means that the attraction will only be open to the public for 100 days during next year, with July and August the only months when the heritage site will be open every day.
Berkeley Castle, which is still owned by the Berkeley family, dates back to 1117, when it was constructed on the orders of Henry II.