Frederic Aumonier says: "From the earliest times man has longed to conceal the baldness of mud walls, canvas tents or more substantial dwellings, by something of a decorative character. Skins of animals, the trophies of the chase, were probably used by our remote ancestors for ages before wall-paintings and sculptures were thought of. The extreme antiquity of both of these latter methods of wall decoration has recently received abundant confirmation from the valuable work done by the Egyptian Research Department, at Hierakonopolis, where wall-paintings have been discovered in an ancient tomb, the date of which has not yet been determined, but which is probably less than seven thousand years old; and by the discovery of ancient buildings under the scorching sand dunes of the great Sahara, far away from the present boundary line of habitable and cultivated land. The painted decorations on the walls of some of the rooms in these old-world dwellings have been preserved by the dry sand, and remain almost as fresh as they were on the day they left the hand of the artist, whose bones have long since been resolved into their native dust."
From the Encyclopædia Britannica I condense the long article on "Mural Decoration":
There is scarcely one of the numerous branches of decorative art which has not at some time or other been applied to the ornamentation of wall-surfaces.
I. Reliefs sculptured in marble or stone; the oldest method of wall decoration.
II. Marble veneer; the application of thin marble linings to wall surfaces, these linings often being highly variegated.
III. Wall linings of glazed bricks or tiles. In the eleventh and twelfth centuries, the Moslems of Persia brought their art to great perfection and used it on a large scale, chiefly for interiors. In the most beautiful specimens, the natural growth of trees and flowers is imitated. About 1600 A. D., this art was brought to highest perfection.
IV. Wall coverings of hard stucco, frequently enriched with relief and further decorated with delicate paintings in gold and colors, as at the Alhambra at Granada and the Alcazar at Seville.
V. Sgraffito; a variety of stucco work used chiefly in Italy, from the sixteenth century down. A coat of stucco is made black by admixture of charcoal. Over this a second very thin coat of white stucco is laid. The drawing is made to appear in black on a white ground, by cutting away the white skin enough to show the black undercoat.
VI. Stamped leather; magnificent and expensive, used during the sixteenth and seventeenth centuries, in Italy, Spain, France, and later in England.