Abstract: Urban underground spaces are mostly used to assist urban surface spaces planning. To a certain extent, the current conventional business model of the underground street/metro station systems disregards their military usefulness. Integrating military features into urban space systems is a difficult problem and requires higherlevel development. In this paper,  ideas for the structural modes, infrastructures, and functional positioning of the underground space in the future are proposed. The main structure of an underground street/metro station system is expanded horizontally and vertically, considering emergency refuges, medical rescue and supplies access, [JP2]as well as psychological construction in emergency situations. The military features are added based on militarycivilian and peacetimewarfare integration, and the horizontal and vertical passages are connected with the main structure. Thus, the working concept of the City Ark is developed.

Key words: urban underground space, emergency response, shelter; disaster prevention and mitigation