Describing routes is an easy everyday task for people who know the environment well. However, strategies exist also for situations where only incomplete knowledge is available. We present a study eliciting verbalized route plans and think-aloud data from novices and experts who were asked to find and describe routes in a complex building. The spatial descriptions were analyzed relating the level of knowledge to route efficiency, and to occurrences of particular linguistic elements. Results reveal a diversity of wayfinding and description strategies, ranging from generic methods via building specific strategies to classic turn-by-turn directions. Experience with the building predicted the performance in finding efficient paths as well as the extent to which concrete spatial elements and uncertainty or orientation markers occurred in the descriptions. These findings open up the possibility of predicting the expertise of a speaker from the form as well as the contents of a route description.