Houses were usually built of sun-dried brick on a stone foundation. The roofs were often flat and were sometimes covered with hardened mud, but tile roofs were also common. Marble for columns and other decorative features was introduced into Rome in the later part of the Republican period and colored marbles were used freely by the rich Romans of the Empire. Walls were covered with stucco, which was frequently painted. There was no wall-paper, of course, and pictures were painted directly on the walls. Fashions in decoration changed as they do at present, though more slowly. The wall-paintings from a villa near Boscoreale, in the Eighth Room, illustrate several types in use in Italy in the first century A.D. The earliest style imitated columns, marble panels, or other ornamental features employed in buildings. Arabesques and fanciful combinations of foliage, birds, animals, and masks came into use later. Mythological and genre scenes, as the lady with the kithara (fig. 21) and the group of a man and a woman seated side by side, required a skilful painter and were naturally reserved for the principal rooms. In the cubiculum (fig. 22) another style has been employed, in which buildings, arches, porticoes, and gardens are combined in a way which, while of course somewhat fanciful, still probably represents the general appearance of the streets and houses of Pompeii and other cities of the time. Stucco reliefs, of which there are several graceful examples in the Museum, were used in Greek houses of the Hellenistic period as well as in Italy. [Illustration: FIG. 23. MOSAIC PICTURE] Floors in early times were of hardened earth, paving stones, or plaster. In the fifth century pebbles set in cement came into use in Greece, and from this kind of floor mosaic, plain and patterned, was derived. Pictures or decorative designs made of fine glass mosaic were also used as wall decorations. Three examples are on the tops of Cases 1 and 2 (fig. 23). [Illustration: FIG. 24. OLD MAN SEATED ON A KLISMOS]