In recent years, the permeability of the Iron Curtain seems to have become a new paradigm in the field of post-war history – urban history included. It is clear, however, that significant differences existed among Eastern Bloc countries in terms of how open they were to Western influences, and to what extent their governments allowed those countries’ citizens – professionals among them – to gain experiences abroad. This article investigates the ways city planning and heritage policy in state socialist Hungary were influenced by international trends; it explores the roles Hungarian architects, urban planners and other experts played after 1956 in knowledge transfers, i.e. the transmission of novel ideas in the field of architecture and urban planning, with special regard to the renewal of inner-city areas and historic town centres. Besides reflecting critically on concepts of the strict East–West divide, the article also calls attention to the limits of freedom inherent even in a relatively liberal Eastern Bloc regime: various forms of state control – including state security surveillance – continued to characterize the system until its collapse in 1989, affecting the mobility of urbanists and architects as well as all other professional groups.