Art Historian and poet. At his death he was succeeded by Eduard Dobbert.

Architectural and sculpture historian of classical Greece and Rome; specialist bronze statuary; NYU professor, 1935-1960. Lehmann was raised Lutheran from cultured parents were of Jewish ancestry. His father was a Professor of Law. Lehmann studied under Ferdinand Noack at Tübingen, under Heinrich Wölfflin in Munich, as well as Göttingen in the years directly before World War I. During the war he served in the Red Cross for Germany and as an interpreter for the Turkish navy, the latter giving him access to much of Asia Minor.

Curator of the antiquities collection at the Koniglichen Musuem in Berlin, 1908-1925, and curator of the sculpture collection at the Albertinum Museum in Dresden 1925-1934.