Studies of art history, Christian archeology and philosophy at the University of Heidelberg, PhD (1989), German Habilitation at the Free University of Berlin (1995), Directeur d’études invité of the EHESS, Paris (1997), Richard Krautheimer Professor at the Bibliotheca Hertziana (2001/02), Chair of Art History at the University of Trier (1998-2003). Visiting Professor: HU Berlin (1994/95), Vienna (1996/97), Basel (2000/01), Buenos Aires (Getty Foundation) (2002), Mexico City (2003). Director and Scientific Member at the Art History Institute in Florence - Max Planck Institute (since 2003).