The owners of Cockermouth Castle are taking advice from structural engineers to find the best way of protecting the ancient monument.
A landslip under the oldest part of the Norman castle has left it exposed.
Last month's floods triggered a landslide which washed away all the vegetation under the grade one listed building which overlooks the River Derwent.
A contractor installed rock armour shortly afterwards, to protect the base of the embankment from further flood and erosion damage.
A spokesman for Leconfield Estates, which owns the castle, said: "Following the remedial work which was undertaken to stabilise the bank we continue to monitor the situation in conjunction with taking advice from structural engineers and building surveyors."
Darren Ward, Cockermouth Civic Trust's architectural advisor, said: "The stonework they have put in has protected from further undermining this week. Without it, and with the river rising, it could have caused some serious problems.
"It won't survive if it's left as it is, it needs stabilising.
"I'm not a structural engineer but I would have expected to see some kind of pinning taking place to stabilise the existing bank and stop further slippage."
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