Buildings and non-archimedean flag varieties by Annette Werner (Frankfurt) in Arithmetic, Motives and Moduli Spaces 9-13 January 2012 A conference organized by Olivier Debarre (ENS), Hélène Esnault (Essen), Claire Voisin (IMJ) et Olivier Wittenberg (ENS) on the occasion of the extended stay of Hélène Esnault, recipient of the Foundation's Chaire d'Excellence 2011.