PILASTER (Fr. pilastre, med. Lat. pilastrum, from pila, a pillar), in architecture, an engaged pier projecting slightly from the wall, and employed to divide up and decorate a wall surface or to serve as respond to a column. One of the earliest examples (c. TOO B.C.) exists in the propylaea at Priene in Asia Minor, where it tapers towards the top. Pilasters have bases and capitals and are frequently fluted like columns. The Romans would seem to have preferred semi-detached columns, but for their amphitheatres sometimes pilasters are employed, as in the upper story of the Colosseum. In the revival of Classic architecture, and especially in Italy, architects seem to have considered that no building was complete without a network of pilasters on every storey, and France and England followed their example; and not only externally but inside the great cathedrals and churches the pilaster is adopted as the simplest and best way of dividing the bays.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)