In the second half of the twentieth century, the concept of indeterminacy in architecture emerged to address the realities of chance and change, with the megastructure representing a critical point of this ambition. As the aims of indeterminate architectural approaches align with current sustainable development goals, this study hypothesises this design concept as the basis for the sustainability of structures built within its framework. Through a case study of Spens, a socialist megastructure in Novi Sad, Serbia, the paper explores the potentials of megastructures in relation to requirements for more sustainable cities. Firstly, it evaluates Spens’ current social sustainability through focus group discussions analysing sense of community, place, and wellbeing. Findings demonstrate a clear recognition of Spens’ spatial qualities among users. Secondly, the paper examines the future environmental sustainability of Spens, focusing on strategies that enhance user wellbeing and urban life as a point of overlap between social and environmental sustainability, using the Green Space Factor (GSF) and Urban Greening Factor (UFG). Results reveal the significant yet underutilised potential for greening. The paper highlights the long-term societal value of such structures and strategies for leveraging their concepts for their sustainable adaptation rather than replacement amid ongoing retrofit or replacement debates.

In the absence of an established city planning strategy, the initial post-war urban development of the SFRY was founded on the principles of CIAM’s “Functional City”, which soon proved inadequate in responding to individual user needs and in reflecting the collective interests of the young socialist state. This paper positions the search for a new spatial expression of the young socialist state within the global architectural discourse of the second half of the twentieth century, which shifted towards more variable, open and indeterminate architectural models employing various forms of user participation. The characteristics of a new approach in Yugoslav architectural and urban planning practice are examined through the case study of an unrealised project for the Mišeluk zone in Novi Sad developed in the late 1970s and early 1980s. The aim of this paper is to analyse the socialist response to a dominant theme of architectural discourse that is once again gaining traction in the theory and practice of contemporary architects, in order to establish a basis for the further development of these ideas in the contemporary post-socialist context. The research reveals a direction for urban planning practice based on user participation, which enables a higher level of versatility or multivariance of the design concept as a response to the individual and changing needs of users, but also as a way of achieving the resilience, i.e., adaptability of architecture in the face of unpredictable social trends.

In the second half of the twentieth century, the concept of indeterminacy in architecture emerged to address the realities of chance and change, with the megastructure representing a critical point of this ambition. As the aims of indeterminate architectural approaches align with current sustainable development goals, this study hypothesises this design concept as the basis for the sustainability of structures built within its framework. Through a case study of Spens, a socialist megastructure in Novi Sad, Serbia, the paper explores the potentials of megastructures in relation to requirements for more sustainable cities. Firstly, it evaluates Spens’ current social sustainability through focus group discussions analysing sense of community, place, and wellbeing. Findings demonstrate a clear recognition of Spens’ spatial qualities among users. Secondly, the paper examines the future environmental sustainability of Spens, focusing on strategies that enhance user wellbeing and urban life as a point of overlap between social and environmental sustainability, using the Green Space Factor (GSF) and Urban Greening Factor (UFG). Results reveal the significant yet underutilised potential for greening. The paper highlights the long-term societal value of such structures and strategies for leveraging their concepts for their sustainable adaptation rather than replacement amid ongoing retrofit or replace debates.

Urban regeneration in Serbia is shaped by complex and competing public, private, professional and community interests, while the existing planning framework lacks a structured pre-planning methodology for examining these interests, contextual conditions and alternative development trajectories before formal planning decisions are made. This study aimed to address this gap and support the articulation of common interest in sustainable urban regeneration. The research synthesised an analysis of the Serbian regulatory and strategic framework and a review of international policy frameworks into a set of methodological requirements, which were translated into an operational Phase 0 framework comprising an analytical layer, a strategic layer and subsequent implementation through existing planning and design instruments. The resulting methodological framework integrates interdisciplinary spatial analysis, stakeholder and interest identification, measurable and interpretative indicators, scenario development and evaluation, and the formulation of a documented strategic orientation. The principal contribution lies in the integration of these otherwise distinct analytical, participatory and scenario-based functions into a single pre-planning framework in which objectives, alternatives, trade-offs and potential consequences can be examined while development directions remain open to revision. The proposed methodology provides a basis for more transparent and anticipatory decision-making in Serbian urban regeneration.