[91] The architrave is properly the horizontal piece of stone laid across the tops of the pillars in Greek buildings, and commonly marked with horizontal lines, obtained by slight projections of its surface, while it is protected above in the richer orders, by a small cornice. CHAPTER XXIX. THE ROOF. § I. The modes of decoration hitherto considered, have been common to the exteriors and interiors of all noble buildings; and we have taken no notice of the various kinds of ornament which require protection from weather, and are necessarily confined to interior work. But in the case of the roof, the exterior and interior treatments become, as we saw in construction, so also in decoration, separated by broad and bold distinctions. One side of a wall is, in most cases, the same as another, and if its structure be concealed, it is mostly on the inside; but, in the roof, the anatomical structure, out of which decoration should naturally spring, is visible, if at all, in the interior only: so that the subject of internal ornament becomes both wide and important, and that of external, comparatively subordinate. § II. Now, so long as we were concerned principally with the outside of buildings, we might with safety leave expressional character out of the question for the time, because it is not to be expected that all persons who pass the building, or see it from a distance, shall be in the temper which the building is properly intended to induce; so that ornaments somewhat at variance with this temper may often be employed externally without painful effect. But these ornaments would be inadmissible in the interior, for those who enter will for the most part either be in the proper temper which the building requires, or desirous of acquiring it. (The distinction is not rigidly observed by the mediæval builders, and grotesques, or profane subjects, occur in the interior of churches, in bosses, crockets, capitals, brackets, and such other portions of minor ornament: but we do not find the interior wall covered with hunting and battle pieces, as often the Lombardic exteriors.) And thus the interior expression of the roof or ceiling becomes necessarily so various, and the kind and degree of fitting decoration so dependent upon particular circumstances, that it is nearly impossible to classify its methods, or limit its application.