Maggid's most important work was "Ir Wilna", the first volume of which appeared in Vilna in 1900; it contains the biographies of more than three hundred prominent rabbis, preachers, and communal workers. The notes alone, referring to genealogical literature, show that the author was familiar with responsa literature as well as with general rabbinical and historical works in Hebrew literature.
Maggid's most significant contribution was "Ir Wilna", the first part of which appeared in Vilna in 1900; it includes biographies of over three hundred notable rabbis, preachers, and communal leaders. The notes alone, concerning genealogical literature, imply that the author was familiar with responsa literature as well as Hebrew rabbinical and historical works.