Council chiefs have told youngsters they are 'putting their lives at risk' by scaling a castle in Derbyshire.
On two occasions in the last fortnight, trespassers who are believed to be aged between 12 and 15 have climbed on to the roof of Elvaston Castle, near Derby.
Derbyshire County Council, which owns the castle, said a 'fall from this height could prove fatal'.
The authority has now increased security patrols at the Grade II-listed building, which is currently being refurbished.
A council spokesperson said: "On both occasions staff have heard them on the roof and they have been shouted at to come down safely.
"People are putting their lives at risk and we'd appeal to parents to impress on their children how extremely dangerous this is."