Passing through this magnificent hall, we gain the peristyle or open quadrangle, which forms so important a part of the Greek house. This is perhaps adorned with flowers and shrubs, or, in a country villa, shaded by a few plane-trees. Porticoes for air and exercise, some of them open to the south for the luxury of basking in the sun, to express which the Romans had a separate word in their language; cool summer-rooms, fronting north, and opening into ornamental gardens, with rows of fantastically-clipped trees; private withdrawing-rooms, bedrooms, baths, terraces and a library, complete the scene of comfort and luxury. These rooms were added according to the wealth or taste of the owner; they were not arranged on a regular plan as in modern houses. The exterior of the house was frequently faced with marble; but, owing to the want of plan and the lowness of elevation, it was usually destitute of effect, though presenting so much splendor internally. The outer door, however, was of striking height, and often surmounted by an elegant cornice. The door-posts of the wealthy were richly inlaid with ivory, tortoise-shell, or even more costly material. The door itself consisted of two halves meeting in the centre, each of which was broad enough to allow two persons to pass. In the days of luxury, precious woods, marble and bronze were in common use among the upper class, for the construction of this outer door. The door turned upon pivots, which either worked in sockets in the sill and lintel, or were encircled by metal rings--the ordinary form of metal hinges being never employed. It was furnished with a circular knocker, and closed by bolts and locks, the remains of which show a skill in the locksmith’s art by no means contemptible. The floors of the Roman houses were not boarded. In plainer dwellings they were covered with a mixture of fragments of stone and mortar, or with pavement of brick, stone, or common tiles. But in great mansions the floor was one of the special points for display. It was either formed of white, black, or colored marbles, arranged in a check pattern, or it was a specimen of elaborate inlaid work. The tesselated pavements, of which so many remains exist, display two varieties. The first, or plainer kind, is formed of tiles moulded into various forms of animals, flowers, or such devices, each tile being a perfect figure in itself. The second, or real mosaic, was composed of pieces separately formless, but put together in a pattern. The most costly kind of this formed a beautiful inlaid painting composed of highly minute fragments, and representing animals, landscapes, historic, or other scenes. The fragments composing this fine mosaic were of glass, earthen-ware, marble, or even precious stones, as agate and onyx. So minute were they, that one hundred and fifty have been found on a square inch of surface.