Once used for national defense, underground fortresses are now being renovated into modern emergency facilities to counter disaster risks, injecting new safeguards into urban public safety. These robust underground structures, leveraging their inherent protective capabilities and vast space, are being systematically converted into safety hubs integrating emergency command, material storage, and personnel shelter. Equipped with comprehensive ventilation and gas filtration systems, independent power generation units, and life support equipment, they can provide crucial survival guarantees for the public during earthquakes, extreme weather, and even public emergencies. Safety experts note that transforming historical defense facilities into dual-purpose (peace-time and disaster-time) emergency venues is a strategic activation of idle resources. This renovation not only significantly enhances cities’ overall disaster resistance and resilience but also constructs a solid   underground lifeline. As urbanization accelerates and disaster forms diversify, this protective model that combines historical heritage with modern technology is expected to offer a replicable new paradigm of emergency solutions for more cities.