The following list more or less follows the order found in the traditional Provinciales, but corrects errors in those in Eubel and other reference books. The assessment for common services is given in florins in brackets behind each see. The list is based on sees in existence in 1400; changes down to 1500 are recorded. Only sees in the area of modern mainland Italy are given, save for those in Istria (above p. x). In the list modern names are given, but in the index Latin names are also given when they are markedly different. Metropolitan sees are printed in italics. Those sees immediately subject to the pope, i.e. not in a province, are termed i.s. From 1 to 65 all are i.s.

It had been hoped to illustrate the following list with a map or maps but investigation showed this to be extremely difficult and expensive. Happily the reader with a magnifying-glass can turn to plate 26 by Th. Menke in K. Spruner and Th. Menke, Historische Handatlas, 3rd ed. (Gotha 1880); it is better for the early and central Middle Ages than for our period. There are also now the magnificent plates accompanying the various volumes of the Rationes decimarum Italiac published in the Vatican series, ‘Studi e testi’, nos. 58, 60, 69, 84, 96–7, 98, 128, 148, 161–2 (Città del Vaticano 1932–52); these cover in effect the dioceses of mainland Italy with the exception of Lombardy and Piedmont but are basically concerned with the thirteenth and fourteenth centuries, so that changes recorded in the following lists are not depicted.