Ferdinand Gregorovius (1821–1891) was a celebrated German medieval historian. After studying philosophy and theology at the University of Königsberg, Gregorovius moved to Rome in 1852, and became immersed in researching the medieval history of the city. First published in 1872, his monumental study of medieval Rome was the first modern account of the subject, and became the standard reference. This English translation of the fourth German edition appeared between 1894 and 1902. In his work Gregorovius discusses the political, social and cultural changes in the city from 400 to 1534, making extensive use of primary sources. Gregorovius also includes the Renaissance in his study, showing how medieval thought and events influenced political and cultural life and thought during the Renaissance. Volume 5, Part 1 covers the period 1200–1260, and examines the relationship between Pope Innocent III and the Holy Roman Emperor Fredrick II.