Repairs need to be carried out to the Northumberland Hall in Alnwick after part of the ceiling collapsed.
A county council spokeswoman said: “We received information about this collapse last Thursday and attended the hall on Friday morning, when we assessed the damage and repaired the roof leak which had caused the ceiling to fall.
“Our contractors had to get a specialist company to clear the bird guano from the roof area. They cleaned up the stairwell and made the ceiling safe for the functions booked over the weekend.
“We are currently checking with conservation colleagues for any restrictions to the repair, as the building is listed. When we have their clearance we will schedule full repairs for a time when the hall is not booked, as the whole stairwell will need to be scaffolded for access and a working platform.”