Roman Uses of the Orders
Structural Use of the Orders
In Roman architecture, the orders continued to be used structurally in places where support for the roof was needed but a solid wall was not.
Columns were also used inside buildings such as basilicas to support the roof and divide the space.
Decorative Use of the Orders
Monumental Use of Columns
Although they were crowned by statues, colossal free-standing columns formed the main element of these monuments in which the column was at once functional as a support and decorative as a monument.
Monumental Roman columns reached their zenith in size and decorativeness with the Column of Trajan and the Column of Marcus Aurelius, which were both ceremonially Christianized and given Christian finials by Pope Sixtus V.
The Romans invented two variations on the column that facilitated its application to arcuated structures as decoration.
|●||Pilasters. The pilaster is a flattened version of a column in which the column is reduced to a decorative strip having the standard parts and proportions of the orders. As illustrated by the use of column-like devices on the upper story of an Etruscan gate in Perugia, this practice had precedent in Etruscan architecture.|
|●||Engaged columns. A column that appears to be embedded in a wall is an engaged column. Sometimes whole columns were built into a wall, as they were at the Monument to Lysicrates, but usually 1/2- or 3/4-round columns with flat backs were attached to the wall.|
Columns Used to Carry Arcades
The first use of columns to carry arcades, which were typically supported by piers, did not take place until late in Roman history. Their use at Diocletian's Palace in Split, Croatia would not have been known to Italians in the Renaissance.
In conjunction with columns, pediments were used to create tabernacles, niches that served as religious shrines.
In late Roman architecture, pediments were sometimes used as decorative caps above openings. As decorative caps, triangular pediments might be alternated with segmental pediments, whose upper member is an arc of less than a semicircle.
Pediments Containing Arches
Pediments with Broken Planes
Placement on Arches and Arcades
When used as decoration in Roman architecture, the orders were most commonly placed on arches and arcades so that columns were centered on piers and entablatures passed above arches. The combination of arches decorated by columns carrying an entablature is the principal motif of the triumphal arch.
Some architectural historians refer to this combination as the arch order.
Placement on Multiple Stories
The orders are often superimposed on successive stories of arcades. Usually each story has a different order, and their arrangement follows an upward progression from heavy (Doric engaged columns) to light (Corinthian pilasters).
Arch of Tiberius, Orange, France