Abstract: A navigation system includes an input module, a spatial database and a routing subsystem. The input module is for user inputting a data of an origin and a destination. The spatial database has a coordinate system and includes a data for point of interest, a way, a path and an area. The path is vertical to ground. The way is parallel to ground. The routing subsystem is connected to the spatial database, and includes a storing unit electrically connected to an operating unit. The storing unit stores the output from the spatial database. The operating unit enumerates all feasible routes between the origin and the destination according to the input data and the coordinate system, and operates the feasible routes to get an optimum route according to the data for the way and the path.