En publiant en francais cet ouvrage, dont une premiere version a d'abord paru en grec sous les auspices de l'Academie d'Athenes, l'Ecole francaise d'Athenes fait connaitre les recherches d'une grande specialiste du Peloponnese franc et byzantin, Aspasia Louvi-Kizi, dont le travail revele toute la complexite des formes architecturales, des emprunts et des modeles reperables dans les monuments de la ville byzantine et medievale de Mistra.Parmi les creations architecturales du couple de despotes, Manuel Cantacuzene (1349-1380) et son epouse Isabelle de Lusignan, qui a faconne Mistra en un centre de pouvoir, Aspasia Louvi-Kizi analyse deux de ses monuments emblematiques, les monasteres de la Peribleptos et de la Pantanassa, proposant une nouvelle histoire de leur construction.Des elements de l'art franc, c'est-a-dire occidental ou gothique, etrangers a la tradition byzantine locale, ont ete incorpores dans leur architecture. Distincts de la production franco-byzantine de la principaute voisine d'Achaie, ces elements gothiques de Mistra ont plutot a voir avec l'art occidental de Chypre; la contribution d'Isabelle a leur introduction dans le Peloponnese est alors determinante. Ces elements occidentaux, qui ornent les clochers et les tours sur les facades, sont combines avec les elements byzantins et constituent une veritable expression de la politique pro-occidentale du couple de despotes, en symbiose avec la politique imperiale de Constantinople a l'epoque.Dans le monde fragmente et multipolaire de la Mediterranee orientale a la veille de la conquete ottomane, ce livre met ainsi en lumiere le role de Mistra en tant que centre regional de pouvoir et contribue a sa reinterpretation.En poursuivant ce dialogue international sur un site de renom, l'Ecole francaise d'Athenes dit aussi son attachement aux regards croises qui font emerger la complexite des echanges a l'oeuvre dans cette histoire d'un monde grec en transition.In publishing this book, an early version of which was first published under the auspices of the Academy of Athens, the French School at Athens highlights the research work of Aspasia Louvi-Kizi, an eminent specialist in the Frank and Byzantine Peloponnese, whose work reveals all of the complexity of the architectural forms, influences and models at work in the monuments of the medieval Byzantine city of Mystras.Out of all of the architecture created by the despotic couple formed by Manuel Cantacuzene (1349-1380) and his wife Isabelle de Lusignan, who were instrumental in turning Mystras into a centre of power, Aspasia Louvi-Kizi focuses on two of the city's most iconic monuments, the monasteries of Peribleptos and Pantanassa, proposing a new history of their construction.Their architecture incorporates elements of Frank art, meaning western or gothic art, which were foreign to the local Byzantine tradition. The gothic aspect of Mystras' architecture, as distinct from the Franco-Byzantine influences in the neighbouring crusader principality of Achaea, has more to do with Western art in Cyprus, and its introduction by Isabelle to the Peloponnese was to prove decisive. The Western elements that decorate the facades of clocks and towers, combined with the Byzantine features to constitute a concrete expression of the despotic couple's pro-Western politics, in line with the imperial politics of Constantinople at the time.In the fragmented and multipolar world of the Eastern Mediterranean on the eve of the Ottoman conquest, this book highlights the role Mystras played as a centre of power in the region and, in doing so, contributes to a fresh take on the city as a whole.By continuing the international conversation about a renowned site, the French School at Athens shows its commitment to a multi-layered approach that reveals the complexity of the interactions at work in the history of the Greek world in transition.