IN A BRILLIANTLY SUGGESTIVE ARTICLE, the urban historian Lewis Mumford defined the form of the “archetypal city” as follows: First of all, the city is the creation of a king…acting in the name of a god. The king's first act, the very key to his authority and potency, is the erection of a temple within a heavily walled sacred enclosure. And the construction of another wall to enclose the subservient community turns the whole area into a sacred place: a city. (12) This ancient city, which arose just before the beginning of recorded history, is double walled. It has an inner as well as an outer boundary. The outer walls enclose the area inhabited by a subservient population, but the city itself exists for the sake of the temple and its adjoining palace, the homes, respectively, of the god and the king. Some great historic city centers such as Rome with its Vatican, Moscow with its Kremlin, and Beijing with its Heavenly City preserve a structure that is apparently descended from this model. In Anglo-Saxon London, however, an abbey and a seat of government were established at Westminster, just outside what became the walled City overlooked by the grim citadel of the Tower. Canterbury, not London, became the nation's religious capital. London, in effect, marks a stage in the separation of spiritual and temporal powers and, thus, in the secularization of the city. Medieval London was able to assert its independence from the monarchy through the institution of its self-governing Corporation, presided over by the Lord Mayor. The mayoralty was the only significant temporal office in the land not in the gift of the king; and this explains why, in the folk-tale, the ragged boy Dick Whittington could become Lord Mayor of London.