Order of architecture denotes any of several styles of classical or Neoclassical architecture that are defined by the particular type of column and entablature they use as a basic unit.
The three Greek architectural orders are Corinthian, Doric, and Ionic. Doric is the oldest, simplest, and most massive of the three Greek orders The Ionic was used for smaller buildings and interior. The Corinthian order is similar to the Ionic order in its base, column, and entablature, but its capital is far more ornate, carved with two tiers of curly acanthus leaves.
