Important historical features at a Cornish beauty spot and nearby town, including a medieval street and a historic former foundry, will receive greater protection.
Conservation areas in St Austell and Charlestown have been extended following a public consultation last year to protect areas of special architectural and historic interest at both locations.
The historic port of Charlestown has great cultural and historic significance as being one of the finest examples of a late-18th to early 19th century industrial harbour in Britain, and the best-preserved china-clay and copper ore port of its period in the world.
Part of the conservation area at the World Heritage Site was designated too tight and the boundary has now been extended to include the ropewalk, a Sunday school and Charlestown Battery at Crinnis Head, as well as historic remains at the former foundry site.
In St Austell, it was recognised that a conservation area in the town centre had omitted important features, such as medieval radial street patterns, late-19th and early 20th century buildings suggestive of a boom time for the town and the significance of the industrial valley.
Helen Nicholson, Cornwall Council community network manager, said the unitary authority will try and secure funding to restore and conserve some of the historic buildings.
She said:"Having these designations in place will help ensure the protection and enhancement of their special character.
"They will help to ensure that valuable historic buildings, as well as trees and open spaces, are protected."
A conservation area defines an area of special architectural and historic interest. They ensure that new development is sympathetic to the special qualities of the area. It also means residents may have to apply for planning permission for building work that wouldn't usually require it.