The conference "20th Century Great Events" addressed this subject over two days, by proposing a series of case studies set in a historical perspective. These were then supplemented with an interpretation of the effects of these events on an urban and regional scale. The four geographical contexts of Barcelona, Athens, Switzerland and the Ruhr region were then considered in an attempt to draw provisional conclusions and above all to acquire useful suggestions for the coming Milan Expo. A very interesting picture emerged in which the following factors seemed to be decisive: control of timing, programming and implementation; the implementation of projects capable of producing side-affects on the form of the city and of triggering innovative and widespread processes in planning culture; the desire to create new geographical relations, broadening the scale of plans to include the landscape dimension; the capacity to combine both implementation and legacy management processes which are often awkward after the event.
Keywords: Great events; landscape; urban planning.