of
the height. The dimensions of some of the Roman doorways are enormous;
in the temple of the Sun at Palmyra the doorway is 15 ft. 6 in. wide and
33 ft. high; and in the temple of Jupiter at Baalbec, 20 ft. wide and 45
ft. high, the lintel is composed of three stones forming voussoirs the
keystone measuring 7 ft. at the bottom, 8 ft. at the top, 10 ft. high
and 7 ft. 6 in. deep.

All the doorways mentioned above have cornices, and in those at Palmyra
and Baalbec richly carved friezes with side corbels. In the Pantheon
there is a plain convex frieze, but the outer mouldings of the
architrave and the bed-mould of the cornice are richly carved. In the
Byzantine doorways at Sta Sophia, Constantinople, a bold convex moulding
and a hollow take the place of the fasciae of the classic architrave.

So far we have only referred to square-headed doorways, but the side
openings of the triumphal arches of Titus and Constantine are virtually
doorways, and they have semicircular heads, the mouldings of which are
the same as those of the square-headed examples. In Saxon doorways,
which had semicircular heads, the outer mouldings projected more boldly
than in classic examples, and were sometimes cut in a separate ring of
stone like the hood mould of later date.

During the Romanesque period in all countries, the doorway becomes the
chief characteristic feature, and consists of two or more orders, the
term "order" in this case being applied to the concentric rings of
voussoirs forming the door-head. In classic work the faces of these
concentric rings were nearly always flush one with the other; in
Romanesque work the upper one projected over the ring immediately below,
and the employment of a different design in the carving of each ring
produced a magnificent and imposing effect: in the Italian churches the
decoration of the arch mould is frequently carried down the door jambs,
and the same is found, but less often, in the English and French
doorways; but as a rule each ring or order is carried by a nook shaft,
those in England and France being plain, but in Italy and Sicily
elaborately carved with spirals or other ornaments and sometimes inlaid
with mosaic.

The deeply recessed Norman doorways in English work required a great
thickness of wall, and this was sometimes obtained by an addition
outside, as at Iffley, Adel, Kirkstall and other churches.

In France, during the Gothic period, the several orders were carved with
figure s