A plen-an-gwarry or plain-an-gwary (Cornish: Plen an Gwari), is a "playing-place" or round, a medieval amphitheatre found in Cornwall. A circular outdoor space used for plays, sports (especially Cornish wrestling),[1][2] and public events, the plen-an-gwary was a Cornish variant of a construction style found across Great Britain. Formerly common across Cornwall, only two survive nearly complete today: the Plain in St Just in Penwith (50°07′28″N 5°40′51″W / 50.1245°N 5.6807°W) and Saint Piran's Round near Perranporth (50°20′54″N 5°07′24″W / 50.3482°N 5.1234°W).[3][4][5]
The theatre area could be used for local gatherings, sports events, and production of plays. Cornwall culture had a type of play called miracle plays, written in the Cornish language, that were meant to spread Christianity. To capture the attention of the audience, "the plays were often noisy, bawdy and entertaining."[3] The most important work of literature surviving from the Middle Cornish period is Ordinalia, a 9000-line religious verse drama which had probably reached its present form by 1400. The Ordinalia consists of three miracle plays, Origo Mundi, Passio Christi and Resurrexio Domini, meant to be performed on successive days. Such plays were performed in a plain-an-gwarry.[3]