Roman windows were much larger and more varied in type especially after glazing was readily available by c.ad 65, although other materials were in use until the early C18. Thin parchment stretched on a frame, then painted and varnished; parchment painted and coated with linseed-oil; linen painted and coated with white of egg and gum-water and varnished; paper soaked in poppy-oil, mutton suet, or wax; and linen dipped or coated in beeswax were employed. In many cases glazing was found only in the upper part of the window, the lower part having wooden shutters, and this arrangement was commonly found even in Scotland's Royal palaces until comparatively recently (C18). In Classical architecture, windows not only had architraves, but were crowned with entablatures with or without pediments. In grander window-openings, columns or pilasters may be found on either side supporting an entablature, gable, pediment, etc., in which case they are said to be aediculated (see aedicule).
Early medieval windows were small and narrow, often with splays on cills and reveals of jambs to improve the ingress of light, and this type of construction seems to be of considerable antiquity. It was as much controlled by questions of security as by the problems of keeping rain out. Anglo-Saxon windows were of this type, frequently crudely arched, or with lintels at their heads shaped on the soffits to look like small arched openings, or having two stones set diagonally at the top to form triangular heads: in towers of the period, apertures often consisted of two distinct openings between which were turned baluster-colonnettes with exaggerated entasis. Romanesque windows were larger, but were still of the hole-in-the-wall type, splayed, semicircular-headed, and often decorated with billet or chevron mouldings. Romanesque semicircular-headed lights were occasionally paired, separated by a shaft, and contained within a bigger semicircular-headed opening. Circular window-apertures were common, often in gables, but sometimes elsewhere, e.g. the clerestorey lights of Southwell Minster, Notts. In First Pointed Gothic, early window-apertures were tall and narrow (lancets), almost invariably with splayed jambs, having sharply pointed heads, used singly or sometimes in groups of three or five (as in the eastern gables of chancels (e.g. the Lady Chapel of Hereford Cathedral (c. 1220–40), but circles, quatrefoils, and other simple figures were used, especially in plate-tracery. With the transition to early Middle Pointed came Geometrical bar-tracery and Y-tracery. Second Pointed work introduced Curvilinear, Flowing, Intersecting, and Reticulated tracery, the various lights framed by mullions and bartracery. In England, Perpendicular windows had mullions and transoms subdividing ever-larger windows into panel-like lights, the design often continuing repeated as blind panels over the adjacent walls: the main mullions rose from the cill to the head which, towards the end of the medieval period, was usually a very depressed arch, and transoms were often ornamented with miniature battlements. Tudor Gothic window-heads frequently were four-centred arches, but were also fitted within rectangular apertures subdivided by mullions and framed at the top by a pronounced hood-mould dropping down on either side and terminating in Label-stops. This was the usual arrangement in late-medieval domestic architecture. Elizabethan and Jacobean windows in grander houses were often vast, subdivided by mullions and transoms, called grid-tracery.