COLONNADE, in architecture, a row of columns. When a colonnade completely surrounds a building or a courtyard, it is known as a peristyle (q.v.). When it projects as a separate motif or as an entrance porch, it is called a portico (q.v.). Colonnades were frequently used in the Hellenistic period to line the streets of towns in Syria and Asia Minor, and this custom spread throughout the Roman empire; the city of Rome was particularly rich in examples of this usage.
