In Hellenistic Greek and Roman architecture a peristyle (/ˈpɛrəˌstaɪl/; from Greek περίστυλος) is a continuous porch formed by a row of columns surrounding the perimeter of building or a courtyard. Tetrastoon (from Greek τετράστῳον, "four arcades") is a rarely used archaic term for this feature. In the Christian ecclesiastical architecture that developed from Roman basilica, a courtyard peristyle and its garden came to be known as a cloister .