The overall objective of this thesis is to critically address, break down and reassemble the urban development process in post-socialist cities through a set of analyses that covers urban planning strategies, real-estate interventions, participatory and urban design activities. The blurred and distorted morphology of cities worldwide requires dynamic solutions and calls for proper techniques that are spatially and temporally adjusted to local socio-spatial patterns. The theoretical foundations are built upon the ordinary cities approach. It provides a unique assemblage to examine how cities are intertwined with the world, without forgetting social, cultural and historical legacies inherent to each city. The urban development of post-socialist cities is thus perceived as a complex and dynamic system that incorporates discrepant layers of urban decision-making, tracks the level of urbanity through the fluctuating links between urban agency and socio-spatial patterns, and, in general, reveals the contextual processes of maintenance, transformation and change within an urban system. The case study of the Savamala neighbourhood, is not only a scaled example of the pre-socialist material legacy, a socialist cultural and regulatory matrix, and a transitional social reality, but equally the condensed illustration of the multi-faceted circumstances of post-socialist urban development. These elements constitute the exploratory boundaries for research pertaining to a decision-making chain, urban agency networks, and to socio-spatial patterns identified in Savamala through a qualitative data collection. The methodological framework is based on a process-driven, correlational research design that blends two methods. The Actor-Network Theory creates bottom-up logical argumentation to describe urban complexity. The Multi-Agent System serves to track urban dynamics and thus outline the action framework of the research. Data analysis, triangulation and reduction rely on complex actor roles and synthesized networks, the contextualization of interests and interventions, and the distribution of urban system transitions. The combination of overlapping methods and the visualization of data in diagrams deconstructs long-term historical processes. The research findings are three-folded. Firstly, they shed light on the actors and the processes at play in Savamala, unveiling a disbalanced conglomerate of sectors: political (power-mongers), economic (profit-seekers), professional (technicians and apparatchiks), civil and cultural (on the go). The articulation of urban agency in Savamala fundamentally confirms an authoritarian distribution of roles and decisions. The empirical results of the study contribute to the operationalization of several theoretical concepts for practical investigations in ordinary cities around the world. While urban development is interpreted in terms of contextualized urban system transitions, an overarching demarcation of the level of urbanity captures the fluctuations of local socio-spatial capital. The complexity of urban actors, forces, artefacts, and the dynamics of urban networks, interrelations, processes, are depicted as a legible, data-loaded scheme of nodes and links when data is visualised through the MAS-ANT methodological approach. This research furnishes a response to the necessity of altering a deterministic concept of urban research in terms of finding an intermediary between empirical data and their graphical display.