This Paper discusses the experience acquired from the user-compatible development of a digital city model as an aid to urban planning based on the endeavours of a large Austrian city. The method selected was a structured survey of the future users of the "Digital City". In the case in question, the addressee is initially an "internal" client, in other words the staff of the Urban Planning Department. Above all findings it seems vital to work more intensive on common terminology and concepts to facilitate the communication between all those involved in creating digital three-dimensional City Models.