Cambridge, city (1991 pop. 87,111) and district, Cambridgeshire, E central England, on the River Cam. The city, set in flat country, is most famous as the site of the Univ. of Cambridge, and tourism is an economic mainstay. Originally the site of a Roman military camp, Cambridge was an administrative and trading center in Anglo-Saxon times. William I had a fort and mint constructed, and two monastic establishments were built in early medieval times. The university was founded in the 13th cent. Central Cambridge still maintains much of its medieval atmosphere and appearance.   Its noted medieval churches include St. Benet’s or Bene't's, the oldest, dating from the late Saxon period; St. Edward's (begun 12th cent.), where Hugh Latimer preached; St. Mary the Great (1478), the university church; and the Church of the Holy Sepulchre, one of four Norman round churches in England. Cambridge also has varied light industries. High-technology firms, drawing on the university's scientific prominence, have multiplied in recent years, and the city has come to be called "Silicon Fen."