Cultural Sustainability Through Heritage-Led Underground Development: The Case Study

The integration of cultural heritage into sustainable urban development has garnered increasing attention, with a growing recognition of its role in fostering resilient, inclusive, and identity-rich cities. While surface-level monuments often receive the primary focus in heritage conservation, archaeological remains buried beneath cities face escalating threats—particularly from large-scale underground infrastructure projects. Among these, underground transit systems pose the most significant risk due to their spatial extent and physical disruption. This paper addresses the pressing challenge of balancing underground urban development with the preservation of subterranean cultural heritage. Using the Ancient Cultural and Communication Complex “Serdika” in Sofia, Bulgaria, as a case study, this study examines how integrated planning and interdisciplinary cooperation can harmonize heritage conservation with modern infrastructure development. The study explores strategies such as spatial integration, design coordination, and adaptive reuse to embed archaeological remains within transit-oriented public spaces. The Serdica project demonstrates that such approaches not only protect heritage sites but also enhance their accessibility and public value, contributing to strengthened urban identity and increased cultural tourism. The findings highlight the potential of underground heritage spaces to serve as dynamic nodes of cultural exchange and urban continuity. The study concludes that culturally sustainable design of underground public infrastructure-when guided by inclusive planning and heritage-informed strategies—offers a viable path toward sustainable urban futures that respect both development needs and historical continuity.