Restoring the masonry walls of historic buildings requires expert help. Causes of deterioration include penetrating moisture, air pollution, vi brations, and poor structural design or workmanship, with dampness the most frequent. Repointing is the commonest remedy. It calls for correct tooling to match the original joint and the choice of the right mortar, probably a premixed masonry cement. Among cleaning methods the author advises against sandblasting, urges caution with chemical cleaners, mentions pressurized water and steam methods with precautions and describes hand brushing with non-ferrous wire brushes. -- AATA