 He became docent of the history of art at Göttingen in 1881, professor there in 1882, at Breslau in 1885, and went to Florence in 1892, and thence to Leipzig in 1893.In 1888 he founded the "Kunsthistorisches Institut in Florenz" (Institute for the History of Art, Florence), an institution to promote original research in the history of Italian art, now part of the Max Planck Society, a German state institution.His writings are characterized by sound scholarship and acute criticism.