Chichester (chĬ´chĬstər), city and district (1991 pop. 26,050), West Sussex, S England. Chichester is an agricultural, retailing, and yachting center and the administrative seat of West Sussex. It has some light industry. Once the Regnum of the Romans, the town was conquered by Ælla and his sons, who landed near Selsey in 477 and later (c.491) founded the kingdom of the South Saxons. In the Middle Ages, Chichester had an important port. A portion of the medieval walls still remains; the 13th-century cathedral stands on the site of an ancient monastery. Chichester has teacher training and theological colleges. The well-known Goodwood motor racing circuit is nearby.