Christian Karl Friedrich Hülsen (born in Charlottenburg, 29 November 1858; died in Florence, Italy, on 19 January 1935) was a German architectural historian of the classical era who later changed to studying the Middle Ages and the Renaissance.
Hülsen was born in Berlin. He studied classical philology, ancient history and archaeology with Ernst Curtius, Johann Gustav Droysen (1808-1884), Emil Hübner (1834-1901), Johannes Vahlen (1830-1911), and Theodor Mommsen (1817-1903). His dissertation, on Ovid, was directed by Mommsen and Hübner. Through Mommsen, he was awarded a stipend from the DAI (Deutsches Archäologisches Institut) to travel to Rome where he assisted in the compilation of the Corpus Inscriptionum Latinarum for the city of Rome. In 1904 he published his Das Forum Romanum, an important and widely translated work on the Roman Forum. As a topographical scholar he gained equal fame with his volume on Roman topography, volume three of Topographie der Stadt Rom in Altertum, appearing in 1907. Despite these accomplishments and his service as second secretary to the DAI in Rome (1887-1909) he was twice denied the appointment of first secretary.
In disillusionment, Hülsen left the institute to live in Florence, where he changed focus to medieval and renaissance art. In Florence he published studies on the historic drawings of Rome by Maarten van Heemskerck, Giuliano da Sangallo, Giovanni Antonio Dosio and other artists. In 1927 his study on the churches of medieval Rome and published Le Chiese di Roma nel Medio Evo. Like his other books in many disparate fields, it represented significant original scholarship. He remained in Florence for the remainder of his life except for five years as professor at the University of Heidelberg. He was the recipient of honorary degrees from Oxford, Erlangen, and New York. Hülsen died in Florence.