This paper introduces the universal mobile interface that allows users to navigate themselves into multiple heterogeneous digital cites with a single interface. The universal mobile interface connects a map-based information search system, an image-based virtual city space, and a 3D virtual city space, that had been developed independently. A user can walk-through the above systems simultaneously, while those systems provide the user with audio descriptions of the scenes. The aims of developing the universal mobile interface are: 1) to provide a single and transparent interface that connects heterogeneous digital cities, 2) to provide audio descriptions of scenes using characteristics of each virtual city space. 1 Why the Universal Mobile Interface?