A 17th Century market hall is being "repeatedly" damaged by lorries colliding with the building, its management has claimed.
The old market hall was built between 1612 and 1622
Work has just been completed to patch up the timber-framed, Grade I-listed building in Llanidloes, Powys, which had been left with "gaping holes".
There are calls for Powys Council to erect signs to restrict lorries from entering the town centre.
The council said illegal parking contributed to the problem.
It added that it was taking steps to tackle the parking issue and would also monitor traffic patterns and erect new signs.
Known as the Old Market Hall, the distinctive building is regarded as a symbol of Llanidloes and was built some time between 1612 and 1622.
But David Stephenson, town historian and a member of the market hall's management committee, said the building was being struck once every two months on average.
He added that the council had "patched up" the market hall, but restoration work was needed inside the building.
"Nothing has yet been done to stop the market hall from being repeatedly hit by heavy lorries," he said.
"This is because of a lack of signage warning off lorries."
Mr Stephenson said warning signs used to exist on the outskirts of town, but were removed when a roundabout was built on the nearby A470.
A Powys Council spokesman said: "It is our intention to undertake monitoring of traffic patterns, which will include signage, in Llanidloes once a sufficient time period has elapsed to allow regular drivers to become accustomed to the traffic calming features.
"Current works around the Old Market Hall will help align large vehicles to minimise the risk of them coming into contact with the structure, or having to mount the pavement."