Gardeners have been banned from cutting grass on steep banks around Carlisle Castle for health and safety reasons.
City councillors have criticised the decision, saying it could deter tourists from visiting the attraction.
English Heritage, which manages the castle, said it had been forced into the decision following advice from the Health and Safety Executive.
The ban involves grass on banks in the medieval castle's moat, which has now become overgrown.
Carlisle councillor Gareth Ellis said: "It is disappointing. People are coming and they are seeing the castle in a mess.
"They see Carlisle's number one landmark like this and they think 'why should I carry on visiting the city?'
"People are almost wanting to drive by because it looks such a mess."
In a statement English Heritage said it was looking at "alternative ways" of maintain the moat area, which is uneven and has steep banks.
The statement went on: "We regularly cut the large areas of grass in front of the castle.
"But following updated guidance from the Health and Safety Executive we have stopped cutting the steep banks in the area of the moat.
"We are looking into alternative ways of maintaining the banks that are in line with the new guidance."