This chapter focuses on issues of the effectiveness of urban plans in the context of contemporary European cities, by mainly considering the subject of the physical transformation of public space connected with building development. The comparison between Turin and Skopje aims to highlight the possible role of urban design tools and planning (especially diachronic visioning), in the future of the sustainable growth of urban European systems. In order for strategies for envisioning the urban plans that are required, to become effective, strong support from political power and economic feasibility is essential. How can we consider the production of plans when this support is lacking? The crisis of the building sector throughout Europe in recent years has underlined some weaknesses of this approach to plans which had been a good instrument from the perspective of economic and physical growth. This paper assumes that the urban plan will continue to be a fundamental instrument for managing the future transformations of our cities, if we are capable of rethinking it as a device for reassembling and including many other implications, beyond those which are usually considered in drawing up the material shape of things to come. The paper will finally attempt to describe some strategies for rethinking the urban plan envisioning from a methodological point of view.