Re-draw architectures as heuristic practice aims to explore the motives, the conception, and the formal and technologic choices, understand the relationship with the original and current context, the transformations, from concept to realization and during the life. In the research the practice of re-drawing, is involving the author along with a group of Master’s candidates, with the contribution of historical disciplines, on case studies relating to Twentieth century demolished, altered or ‘on paper’ architectures. In the teaching, a version of this activity, adapted to the students’ training in the Laboratory of Drawing and Survey, has been proposed, also with input from some lectures by architectural design professors.