This catalogue presents over 300 photographic images of watermarks found in Italian printed maps of the 16th century. Such watermarks are important tools in identifying paper moulds and are part of the evidence that bibliographers use in dating the paper on which maps and other documents were printed. The images reproduced in the catalogue have been selected from some 1200 beta-radiographs of watermarks gathered from Italian printed maps issued mostly in composite atlases printed in Venice and Rome between 1540 and 1600. These beta-radiographs reveal minute variations that are almost invisible to the eye. A special feature of the book is a visual index of miniature black-and-white line tracings of the watermarks. Fifteen years in the making, this catalogue should be of use as a reference for bibliographers and archivists dealing with rare books and maps of the period, map collectors, map librarians, and scholars and librarians working with early printed items and manuscripts.