The ancestor of the masonry column is the wooden pillar. This would be supported by a stone base in order to keep it from rotting at the ground. The use of stone such as marble not only provided greater durability and aesthetic impact but also meant that greater heights could be achieved using a building block approach. Additional mechanical stability could be provided for by introducing one or more metal pins between sections.
The primary stylistic orders of Roman columns were inherited from the Greeks, including the simple “doric”, the scroll “ionic” and the flowery “corinthian”. The style is generally dictated by the capital at the top of the column which holds the architrave (“entablature”) above. The application of Greek proportion clearly added monumentality to the columns and buildings which they formed a part of and Roman understanding of this is evident in their use of the three orders on the exterior of the Colosseum and theatre of Marcellus. Not only were the three stylistic orders used but the columns themselves are only half-columns which underlines the fact that the principal aim of these columns is aesthetic.
The half column is a Roman invention. This is a protruding section of wall made to look like a column which has been walled in. This illusion is enhanced by the introduction of a capital and base in any of the three stylistic orders. Although this “buttress” offers some structural functions such as supporting internal cross beams and reinforcing the wall itself it is really aimed as an aesthetic device. This is made evident in examples such as the small temple to Virile Fortune, in the Forum Boarium by the Tiber. In this case the temple gives the impression of being surrounded by the habitual portico of columns.
The column has clearly always leant itself to commemorative uses and it is not surprising therefore that the first columns Roman columns one will think of are those commemorating emperors Trajan and Antoninus.
These two works of art had little functional purpose other than acting as a monumental tomb for their respective owners. The tomb cell was in the base cavity whilst the commemorative bit was performed by the story-telling sculptural relief which scrolls its way up the column and by a statue of the emperor placed at the top, not to mention the monumental size of the column. The size of the columns is sufficient to allow a small staircase to spiral its way up the centre. A number of windows were dug into the sides to allow light through although the fact that they cut straight through the art work suggests that they were an afterthought. The columns were made of a number of sections which in themselves are huge and one wonders at the skill required to place one section onto the next. The sculptural work was done on scaffolding, once the column had been erected.
The next columns in size are monolithic – ie made of one single piece. The purpose of this was not only functional stability but also aesthetic. There is little doubt that from an aesthetic point of view a single monolith is far more overbearing than a composite column. These monoliths were generally (if not exclusively) of granite or marble because these materials were best able to withstand the tensile forces they would be subjected to during transport and erection on site (through specifically built hoists). A good example of this type of column is to be found holding up the porch of the Pantheon. Each of these granite columns is some 35ft (11m) in height and 5ft (1.5m) in diameter at the bottom. The (Corinthian styled) capitol and base provide some extra height to the units.
The vast majority Columns are made of a number of sections. This was clearly the most convenient means of cutting and transporting the blocks as well as ensuring their integrity during transport. The problem is the loss in stability under earthquake for example, especially when there is a high ratio between height and thickness of the column. Added stability could be achieved by introducing metal bolts between the sections. The bolts would be cemented into place with molten lead.
Decorative elements such as the leaves in the capitol or the channels along the body of the column were hand sculpted. It was not unusual for the aesthetic work to be undertaken after the column had been put in place and could sometimes take a number of years after the building’s completion.
A simpler and cheaper means of making columns was with brick or stone and mortar. In the case of brick columns the individual bricks would be specially shaped into something akin to a petal. The finished column would then covered in plaster and brought to the required level of finish to appear like a marble column.
It seems appropriate to finish off by noting that the last addition to the Imperial Forum was a column placed in the Forum’s central square in honour of Emperor Phocas in the year 608AD. Its purpose was and still is to commemorate the emperor’s donation of the Pantheon to the Christian church. Given that the Roman empire of the West had already fallen over a century earlier we can understand the relative financial and technical poverty of the times which explains why the column was in fact taken from an older monument.