Considered sick from the Modern, the historic town has survived in a fragmentary way despite manyattempts to replace it. Understood as archaeological find it has been the subject, since the 70's, of twoattitudes, which can still be traced in actual urban research: one tried to reintegrate it, according to theprinciple of historical continuity and urban reconstruction, while the other one understood it as afragment in collision with urban complexes, large infrastructures and natural landscapes. Introducedin 1975 by the London exhibition Rational Architecture coordinated by Léon Krier, reconstruction isdefined as central topic of urban research. The exhibition catalogue, published three years later byBrussels AAM directed by Robert L. Delevoy, is presented as a kind of manifesto that address the keyissues of a renewed attitude for typological reconstruction. From this migration of rationalarchitecture in English and, through the catalogue, Belgian territory different forms are delineated,which are rooted in the orientation of the two main schools involved with some of their protagonists.On the one hand, the Architectural Association (AA) in London, directed by Alvin Boyarsky (1971-1990), whose experimental attitude will generate a new generation of architects, among them some ofthe major protagonists of the following decades - from Peter Cook to Bernard Tschumi, RemKoolhaas, Zaha Hadid. On the other, the Institut supérieur d'architecture de La Cambre in Brussels,where, under the direction of Robert L. Delevoy and Maurice Culot, will be given a particularattention to continuity with historic city. To put critical foundation to this reconstructionist line helpthe intense publishing activity, began in 1968, of the Archives d'Architecture Moderne (AAM) inBrussels. Other central events of this line are two meetings held in 1978: from the first, organized byPierluigi Nicolin, will be drafted the Declaration of Palermo, the second one will be the conference heldin Brussels The Reconstruction de la Ville Européenne. Continuing the interrupted existing city becomes afundamental practice of this movement, which introduces the tool of counter-projects, systematicallytheorized by Leon Krier and Maurice Culot, to correct "wrong" projects, mostly resulting from theapplication of Modern principles. This corrective sense of the project is used in a didacticexperimentation with students of Politecnico Milano on different areas in Berlin and Milan PortaNuova trying to solve the fragmented condition of existing urban blocks.