The execution of Cumbernauld New Town was certainly an exceptional representation of town centre design and a fascinating case that converges between modernist’s utopia realisation and typical town planning context. Its a plan shows great ambition to a Utopian modernization and also an aspiration to a complex energy-efficient, technology-dependent mega-structure. Though the project received much admiration and praise at that time, it soon becomes a disappointment of Great Britain, deteriorated in a shabby status. This paper examines the genesis, expansion and reassessment of the bizarre structure. It consists of three main parts. Firstly, it provides the conceptual background of regarding the Central Area as a mega-structure developing strategy and examines the challenges post for Cumbernauld. The second part discusses why the Cumbernauld evolved into its chosen form and evaluate the structural deficiency of this mega-structure. The last section points out the difficulties when consider both ‘density’ and ‘mobility’, and analysis the failure of vehicle separation – the solution adapted to resolve modernity and urban planning. The article points out the design failures and the lacking of adequate political choice during the town planning and further discuss what makes up for quality urban life.   The end of the second world war has stimulated Europeans countries to carry out numerous post-war planning strategies with a modernistic approach to architecture in order to recover and rebuild from the war. In the context of Britain, many new towns were developed following the New Town act of 1946. Cumbernauld Town centre, a brutalist modernism megastructure executed by powerful local political leaders and dominant town planner, was regarded as a creation to the outgrowth of the central government, an extension of the regional planning movement. Ambitiously, the new town was planned with five phases. The failure of Cumbernauld was partially due to the discourse over the question of what is the essence of physical setting for urban life – from functional planning to urbanity, the key value of modern urbanism changes substantially in the 1970s. Just before the second phase, Cumbernauld was still grounded with rationalistic functional planning and a community version of the town. The ideal of ‘community’ was soon replaced by the emphasis on a further utopia idea, ‘mobility’, inspired by American consumerism. Cumbernauld was the first complete version of megastructure that was even to be realised at that time. Unlike other agglomeration -buildings completed in the 1960s, Cumbernauld was not limited only to a small range of functions but has everything needed for an urban living complex. Given that the town was to be seen as a single entity with all infrastructures needed for urban living, it is crucial to make the town centre easily accessed and well connected. Huge Wilson, the chief planner of this project, solely aspired to design a pedestrianised town with a ‘nucleated and compact settlement’, completely neglected geological constraints of his chosen site, Cumbernauld Hill. The site’s narrow and elongated nature has post limitation on the disposition of both roads and buildings. Pedestrians visiting the town centre would have limited and constrained road of access through its stiff gradients on the way and rather than a more uncontrolled disorientated journey of exploration.