Bath and North East Somerset have 663 Grade I listed buildings , one of the highest concentrations in the country , covered by about 100 English Heritage listings . The oldest sites within Bath are the Roman Baths , for which the foundation piles and an irregular stone chamber lined with lead was built during the Roman occupation of Britain , although the current building is from the 18th century . Bath Abbey was a Norman church built on earlier foundations , although the present building dates from the early 16th century and show a late Perpendicular style with flying buttresses and crocketed pinnacles decorating a crenellated and pierced parapet . The medieval era is represented by the remains of the city walls in Upper Borough Walls .