l families.
Many of these are still standing in Bologna. The smaller towers in
which northern architects took so much delight are almost unknown in
Italy, though on a few of the great churches of the north (_e.g._ the
Certosa at Pavia, and St. Antonio at Padua) they are to be found.

The use of constructive columns is general; piers are by no means
unknown, but fine shafts of marble meet the eye frequently in Italian
churches. The constant use of the column for decorative purposes is a
marked characteristic. Not only is it employed where French and
English architects used it, as in the jambs of doorways, but it
constantly replaces the mullion in traceried windows. It is employed
as an ornament at the angles of buildings to take off the harshness of
a sharp corner, and it is introduced in many unexpected and often
picturesque situations. Twisted, knotted, and otherwise carved and
ornamental shafts are not unfrequently made use of in columns that
serve purely decorative purposes.

_Openings and Arches._

The constructive arches in Italian Gothic buildings are, as a rule,
pointed, but it is remarkable that at every period round and pointed
arches are indiscriminately employed for doors and windows, both being
constantly met with in the same building.

The naves of Italian churches rarely show the division into three,
common in the north. The triforium is almost invariably absent, and
the clerestory is often reduced to a series of small round windows,
sufficient to admit the moderate light which, in a very bright
climate, is grateful in the interior of such a building as a church;
but they are far less effective features than our own well-marked
clerestory windows.

[Illustration: FIG. 54.--OGIVAL WINDOW-HEAD.]

The doorways are often very beautiful, and are frequently sheltered by
projecting porches of extreme elegance and lightness. The window
openings are, as a rule, cusped. An ogee-shaped arch (Fig. 54) is
constantly in use in window-heads, especially at Venice, and much
graceful design is lavished on the arched openings of domestic and
secular buildings. A great deal of the tracery employed is plate
tracery.[27] The tracery in terra-cotta has already been referred to.
In the large windows of the principal apartments and other similar
positions of the palaces in Venice and Vicenza, a sort of tracery not
met with in other countries is freely employed. The openings are
square-headed, and are divided into separ