The pilaster is an in classical architecture used to give the appearance of a supporting column and to articulate an extent of wall, with only an ornamental function. It consists of a flat surface raised from the main wall surface, usually treated as though it were a column, with a capital at the top, plinth (base) at the bottom, and the various other elements. In contrast to a pilaster, an engaged column or buttress can support the structure of a wall and roof above.