Accelerating global urbanization underscores the limits of reactive urban planning systems. The Smart City paradigm has facilitated a transition to predictive control; however, traditional development places an increasing strain on infrastructure, contributing to resource depletion and environmental pollution. Urban digital twins (UDTs) have been deployed to retrofit brownfield infrastructure; however, they have not been strategically deployed in greenfield vertical urban projects. This study investigates the adaptation of UDT architecture in NEOM’s The Line, a prototype for vertical urbanism. Strategic documentation was synthesized to evaluate UDT adaptation in greenfield zero-gravity environments. The analysis identified a structural shift from 2D geospatial grids to 3D volumetric stacks, enabled by synchronization using a high-density fiber backbone. The findings indicated that this strategy employs artificial intelligence for predictive operations, dynamic load balancing, and vehicle-to-everything communication. Numerical sensitivity analysis established functional stability bounds, validating the resilience of the orchestration engine, independent of planning intent. However, governance barriers specifically sector siloing persist. Although the technical architecture is sound, the absence of a unified regulatory framework remains a critical single point of failure. This study provides a strategic blueprint for hyper-connected vertical cities.