Chief curator Musées royaux d'Art et d'Histoire/Koninklijke musea voor Kunst en Geschiedenis, Brussels. De Borchgrave was the son of Frédéric de Borchgrave d'Altena (1864-1932) and Marie-Clémentine Blanckart (1869-1960). The family lived in the castle of Lexhy in Horion-Hozémont, near Liège. De Borchgrave earned his doctoral degree in archaeology and art history at the University of Liège under Marcel Laurent. In 1924 he joined in Brussels the Musées royaux d'Art et d'Histoire, directed by Jean Capart.