Mantels and staircases, the most important architectural features of interiors, were very properly elaborated considerably beyond the somewhat negative character of background accessories by the builders of Colonial times. Virtually furnishings as well as necessary parts of the house, the application of tasteful ornamentation to them seems amply justified. Each is a subject in itself, as indicated by the fact that stair building and mantel construction still remain independent trades quite apart from ordinary joinery. For that reason two separate chapters of this book have been devoted to these important subjects, the present chapter being devoted to interior woodwork in general. What the interior wood trim of the average eighteenth-century Philadelphia house consists of is shown by accompanying photographs, especially those in Stenton, Mount Pleasant and Whitby Hall. It is found that the principal rooms of pretentious mansions, such as the hall, parlor and reception room at Stenton, were sometimes entirely paneled up on all sides. About this time, however, hand-blocked wall paper began to be brought to America, and a favorite treatment of Colonial interiors, including halls, parlors, dining rooms and even the principal bedrooms of large houses, combined a cornice, or often a cornice and frieze, and sometimes a complete entablature, with a paneled wainscot or a flat dado with surbase and skirting, the wall between being papered. Sometimes a dado effect was secured by means of a surbase above the skirting, the plaster space between being left white as in the parlor at Cliveden or in the hall and dining room at Whitby Hall, or papered like the wall above, as in the parlor at Whitby Hall and in some of the chambers at Upsala. Later the skirting only was frequently employed with a simple cornice or picture mold, even in the principal rooms of the better houses, as in the dining room at Whitby Hall. Several accompanying illustrations show it with the dado, while a few interiors of Mount Pleasant, Upsala and Cliveden show it with the paneled wainscot. This general scheme constitutes a pleasing and consistent application of the classic orders to interior walls, the dado, the wall above it and whatever portion of the entablature happens to be employed corresponding to the pedestal, shaft and entablature of the complete order respectively. In a room so treated the dado becomes virtually a continuous pedestal with a base or skirting and a surbase above the die or plane face of the pedestal. Usually this surbase is molded to resemble the upper fascia or the complete architrave of the various orders. Again it may be hand-carved with vertical flutings, continuous, as in the parlor at Upsala, or in groups of three or more in alternation with an incised flower pattern, as in the Rex house.