The Canterbury Tales was Chaucer's magnum opus. He used the tales and the descriptions of the characters to paint an ironic and critical portrait of English society at the time, and particularly of the Church. Structurally, the collection resembles The Decameron, which Chaucer may have come across during his first diplomatic mission to Italy in 1372. The tales are told as part of a story-telling contest by a group of pilgrims as they travel together on a journey from Southwark to the shrine of Saint Thomas Becket at Canterbury Cathedral.