The curtain walls of Chester Castle have been undergoing progressive repair and conservation on a year-by-year rolling programme basis. This has involved a very careful study of the existing fabric followed by complex Scheduled Monument Consent procedures. Much of the castle walls had been closed to the public for safety reasons. Arrol and Snell has devised a new scheme of safety railings, access improvements, new paved walkways and drainage improvements, which have allowed the wall walks and upper parts of the fortification to be reopened to visitors. A key aim of the project has been to devise strategies for dealing with rainwater penetration and consequent stone decay problems. Great care has been taken with stone selection and mortar design for all of the repair work.