Cohen (1947-2023) had a doctorate in the history of art and was a graduate of the EHESS. He directed the architectural research programme of the Ministry of Public Works (1979-1983), before holding a research chair at the Paris-Villemin School of Architecture (1983-1996), and then the chair of the History of Cities at the French Institute of Urban Planning at the University of Paris-VIII (1996-2005). In 1994, he was appointed Sheldon H. Solow Professor in the History of Architecture at the Institute of Fine Arts at New York University. In 1997, the Ministry of Culture entrusted him with the creation of the Cité de l'architecture et du patrimoine, where he directed the Institut français d'architecture and the Musée des monuments français until 2003. He was a visiting professor at the Collège de France from 2014 to 2021.
His research activity focused on 20th century architecture and urbanism. He studied the architectural cultures of Russia and Germany, the colonial situations of Morocco and Algeria, architecture during the Second World War, and devoted himself to the interpretation of Le Corbusier's work and the history of urbanism in Paris. A central question in his work was that of cultural transfers in architecture and urban landscape, addressed through the relations between Italy, Germany and France, and recurrently through the interactions between Russia and the West.
Among his more than forty published works are Frank Gehry. Catalogue Raisonné of the Drawings. Vol. 1, 1954-1978 (2020) ; Construire un nouveau Nouveau Monde, l’amerikanizm dans l’architecture russe (2020) ; Le Corbusier : an Atlas of Modern Landscapes (2013) ; Interférences / Interferenzen : architecture, Allemagne, France 1800-2000 (2013,with Hartmut Frank) ; L’architecture au futur depuis 1889 (2012) ; Architecture en uniforme (2011) ; Casablanca, mythes et figures d'une aventure urbaine (1998, with Monique Eleb).
He designed a number of exhibitions, including La temptació d'Amèrica. Ciutat i arquitectura a Europa, 1893-1960, at CCCB of Barcelona (1996), Le Corbusier, an Atlas of Modern Landscapes at MoMA of New York (2013) ; Scènes de la vie future, Architecture en uniforme et Construire un nouveau Nouveau Monde, at the Centre canadien d’architecture in Montréal (1995, 2011 et 2019) ; Interférences, at MAMC of Strasbourg (2013) and Une architecture de l’engagement : l’AUA (1960-1985),at la Cité de l’architecture et du patrimoine (2016) In 2014, he curated the French pavilion at the Venice Architecture Biennale.