The monograph is devoted to the study of one of the most interesting phenomena of Russian historical science - the St. Petersburg school of medievalists, which arose at the beginning of the twentieth century and included a number of outstanding scientists - L.P. Karsavin, N.P. Ottokar, O.A. Dobiash-Rozhdestvenskaya, M. .A. Gukovsky and others. The history of the life, scientific and pedagogical activities and relationships with students of the school leader, Professor I.M. Grevs, is examined in detail.