Use of Columns
Columns were originally used in the porticos and courts of temples and other buildings, and sometimes to form supports for vaulted roofs. Wherever employed their function was directly structural, but this was not the case at the time of the Renaissance. The requirements demanded by widely different social conditions led to their being used more as decorative than structural features.
The use of engaged columns and pilasters in a façade can be justified to some extent. Although such columns and pilasters may not be absolutely essential for support, yet they act as buttresses and add to the strength of the structure with a certain economy of material. Also they are æsthetically satisfactory in their effect of light and shade.