plain and the upper only fluted.
The Attic base was generally used, but an example has been found of an
adaptation of the graceful Persepolitan base to the Corinthian column.
This was the happiest innovation that the Romans made; it seems,
however, to have been but an individual attempt, and, as it was
introduced very shortly before the fall of the Empire, the idea was
not worked out.

The orders thus changed were employed for the most part as mere
decorative additions to the walls. In many cases they did not even
carry the eaves of the roof, as they always did in a Greek temple; and
it was not uncommon for two, three, or more orders to be used one
above another, marking the different stories of a lofty building.

The columns, or pilasters which took their place, being reduced to the
humble function of ornaments added to the wall of a building, it
became very usual to combine them with arched openings, and to put an
arch in the interspace between two columns, or, in other words, to add
a column to the pier between two arches (Fig. 146). These arched
openings being often wide, a good deal of disproportion between the
height of the columns and their distance apart was liable to occur;
and, partly to correct this, the column was often mounted upon a
pedestal, to which the name of "stylobate" has been given.

It was also sometimes customary to place above the order, or the
highest order where more than one was employed, what was termed an
attic--a low story ornamented with piers or pilasters. The exterior of
the Colosseum (Fig. 5), the triumphal arches of Constantine (Fig. 139)
and Titus, and the fragments of the upper part of the Forum of Nerva
(Fig. 147) may be consulted as illustrations of the combination of an
order and an arched opening, and of the use of pedestals and attics.

[Illustration: FIG. 146.--PART OF THE THEATRE OF MARCELLUS, ROME.
SHOWING THE COMBINATION OF COLUMNS AND ARCHED OPENINGS.]

[Illustration: FIG. 147.--FROM THE RUINS OF THE FORUM OF NERVA, ROME.
SHOWING THE USE OF AN ATTIC STORY. WITH PLAN.]

Another peculiarity, of which we give an illustration from the baths
of Diocletian (Fig. 148), was the surmounting a column or pilaster
with a square pillar of stone, moulded in the same way as an
entablature, _i.e._ with the regular division into architrave, frieze,
and cornice. This was a decided perversion of the use of the order;
it occurs in examples of late date. So also do vario