Two Georgian pillars at the top of Ralph Allan Drive are being damaged by large vehicles trying to turn at a new mini roundabout.
The roundabout, at the junction with North Road and Ralph Allen Drive, was installed in March along with bollards and a pedestrian refuge.
Residents say large lumps have been gouged out of both pillars since, which are topped by large urns and are Grade II listed.
They are concerned that a platform, on which one of the large urns sits, has shifted several inches since the damage began.
The pillars were designed by the famous Bath architect John Wood the Elder, who also designed Queen Square and The Circus.
Built around 1740, they were intended to display the quality of stone being quarried from Ralph Allen’s mines in Combe Down.
Ralph Allen, an 18th century entrepreneur famous for reforming the British postal system, lived at Prior Park- now home to Prior Park College.
Martin Coulson, Chair of Combe Down Heritage Society, said the new roundabout was providing welcome relief at a busy junction.
However, large vehicles including school buses now have insufficient turning space to negotiate the roundabout.
He said: “I think probably the highways designer was just a bit over enthusiastic and very keen to have this done as impeccably as he could.
“Highways has recognised this and is starting to put ideas together that the bollards should go and the height of the pedestrian refuge should be lowered.
“In the meantime they need to put some protection on the pillars. Ralph Allen was the man who built Bath, but we don’t seem to be able to be bothered to care for this particular part of his heritage.”
There is a 7.5 tonne weight limit on North Road, but members of the Combe Down Heritage Society say this is “widely flouted”.
They would like Bath and North East Somerset Council to appoint stone masons to fix the damage and reconfigure the roundabout so vehicles can turn safely.
Combe Down councillor Cherry Beath campaigned for the roundabout to be put in place and said the council had been monitoring the situation closely.
She said: “The pillars are held very dear in Combe Down and are listed structures.
“The roundabout itself has been a successful solution to the problems of that junction, however large vehicles have been causing damage, which cannot go on.
“I am working with the council engineers to look to make adjustments as necessary to the crossings. We believe extra large vehicles are using the road because of the temporary closure of the A36.”