Within my diploma thesis I described the development and the evaluation of a prototypic speech-based navigation system for pedestrians named ArriGator. The system responds and guides the user with spoken commands to his destination. It provides full speech assistance within a predefined test area in a German suburb on a set route. The whole guidance is based on landmarks. The dialogue is flexible responsive to the user's questions. The user is able to trigger the system in several ways. Another goal of the prototype was to design the dialogue in a way as to convey spatial knowledge about the test area, such that the user actually gets to know this environment. The following video shows the prototyp in action and was broadcasted on "Regio TV Schwaben" on 9th April 2008.