This paper presents the conceptual framework and technical architecture of Digital Heritage Belgrade—an interactive Geo-Information System (GIS) designed for the systematic documentation, monitoring, and public promotion of Belgrade's architectural heritage mostly from the mid-nineteenth century through the end of the twentieth. The proposed platform addresses a critical gap at the intersection of urban history, digital humanities, and heritage conservation: the absence of an integrated, publicly accessible, and analytically capable digital infrastructure for one of southeastern Europe's most architecturally complex capitals. The system is conceived as a dual-mode open ecosystem combining educational and tourist-oriented interfaces with a professional monitoring layer intended for use by conservators, urban planners, and researchers. Core features include a multidimensional architectural database with filterable attributes, an interactive chronological timeline visualizing the city's spatial development, and a prospective AI-driven component for automated facade condition assessment. The paper outlines the system's key design principles, potential institutional partnerships, and a scalability roadmap.