COLONNA. – It is a supporting element of circular section, generally made of marble or stone, with a base and capital, connected with other similar elements by an entablature or arches; it is intended to withstand the vertical action of the elements above (v. ORDINI ARCHITETTONICI). It may also be used singly or attached to walls and piers, with predominantly decorative functions. The architects of the earliest Christian basilicas made extensive use of it to divide the large space of the church into several naves.
Notable in this period are the vine-patterned columns of the ancient basilica of S. Pietro, intended to enclose the iconostasis, or those adorned with foliage in the choir of S. Prassede. The columns of eastern origin in the ciborium of S. Marco, with representations unfolding in superimposed rings, derive from the type of the Roman figured column. Also worthy of note, at the beginning of the 6th century, are the ornament-covered columns of the ciborium of the priest Mercurio in the church of S. Clemente. During the early Middle Ages, reused columns were employed almost everywhere, and it was only in the Romanesque period that columns acquired new and unusual proportions. Later, at the beginning of the Gothic period, the column often took the form of a spiral composed of three or more elements, and the spirals frequently followed different patterns within the same column, divided by horizontal pauses into distinct sections. At that time, especially in Rome and southern Italy, the shafts were often veined with mosaic. The spiral column disappeared during the Renaissance, when the rigidity of the classical orders was restored. In the transition to the Baroque, the column underwent somewhat freer interpretations of proportion; Bernini, in the baldachin of S. Pietro, drew inspiration from the vine-patterned columns but gave the motif a new coherence; Borromini also used caryatid columns; Fuga covered those of the tabernacle of S. Maria Maggiore with metallic foliage. Bernini’s innovation in particular also had a wide influence on painted perspectives (Frascati, Gesù). Once the rigid ancient rule of proportions had been restored with Neoclassicism, nineteenth-century architecture made extensive use of the column, until the introduction of new building materials—above all iron and reinforced concrete—entirely altered the character of the original relationships between it and the other architectural elements. Guglielmo Matthiae
#### COLONNA, EGIDIO: V. EGIDIO ROMANO.