Regional planning, especially in the Alps, is high on the current news agenda in Switzer- land, more so than ever before. The skiing boom has driven massive urbanisation in mountain areas, primarily in locations at altitudes of 1400m or higher. For several decades this process has occurred with little to no planning, resulting in large inhabited areas comprising sparsely aggregated single-family chalets, the low density of this development model producing an urban sprawl inevitably dependent on car usage. Second homes, which are an important economic driver in the mountains, are the crux of the issue here, regarded as the main culprit responsible for this fragmented and profligate use of land. In 2012, the Fondation Franz Weber (FFW) Second Homes Initiative marked a watershed in the urbanisation of the Alpine region, when the Swiss population voted with a 50.63% majority to ban the construction of new second homes in municipalities where they account for 20% or more of the total housing stock. This initiative certainly has the merit of highlighting the existing situation in the Alps -where new legal, economic and planning solutions are urgently required- but the current proposal fail to convince. Stigmatising urbanisation and densification -as this campaign effectively did, using photomontages designed to shock-does not constitute an adequate response to the Alpine urban sprawl, which is caused not by urbanisation alone, but rather by the dispersal of the built environment. What strategies, then, would safeguard the Alpine region and its landscape without merely clinging to the status quo, which the Weber initiative seems to endorseâ ? Would it not be preferable to further densify the mountain towns that already exist, in order to extend their life cycle and protect other as yet undeveloped areas over the longer termâ ? Shouldnâ t we be developing appropriate mobility infrastructures within the new alpine densificationâ ? These two hypotheses form the core of the present thesis. Following a general theoretical summary of the current major challenges facing the Swiss Alpine environment, this study undertakes a focused analysis of various representative models of high-altitude towns and mobility systems, including Verbier (Valais, Switzerland), Zermatt (Valais, Switzerland), Avoriaz (France), Whistler Blackcomb (Canada) and Andermatt (Uri, Switzerland). The comparative synthesis of these case studies draws on previously unavailable data to demonstrate the limitations not just of the dominant Alpine town model with its sprawling, expansive coverage, but of the compact city, too. Finally, this design doctorate uses spatial experimentation to ascertain the viable maximum size of an Alpine urban unit, defining the critical size for effective densification. The thesis focuses in particular on the case study of Verbier, which is currently reaching saturation point, with land availability constraints, road congestion and climate stresses, quite apart from the fact that the second homes threshold has already been surpassed. In order to solve these various problems our project envisions a new Alpine urbanization, an "inhabited infrastructure", that integrates urban densification alongside public transport. The project illustrates and demonstrates that it is possible, indeed desirable, to densify Verbier further before investing in as yet undeveloped areas.