The Mobile City Explorer is an active, GALILEO based smart travel guide. The Mobile City Explorer navigates the tourist along interesting paths, enables him to take pictures of touristic sights and explains those points of interest to him, contrary to existing solutions, which are limited to map based navigation and passive reference books only. Instead, using the Mobile City Explorer, the user can concentrate on experiencing and exploring the characteristics of the city environment. In addition, the Mobile City Exlporer automatically keeps a multimedia travel diary. This saves the user from the tedious work of documenting, cataloguing and processing his pictures and travel experiences. The multimedia travel diary enables the tourist to "relive" his travel experiences. The combination of a mobile vision based travel guide and a multimedia travel diary represents a high value for the tourist.