Route directions describe the sequence of actions a moving person needs to take to reach a goal in an environment. When generating directions, speakers not only specify what to do. They also refer to landmarks located along the route. We report two studies intended to identify the cognitive functions of landmarks. In the first study, participants learned a route in an urban environment. They then generated route directions to help pedestrians unfamiliar with this environment to find their way. We found that landmarks were reported more frequently at specific points on the route, especially at reorientation points. The second study showed that pedestrians perceived landmarks as a useful part of route directions. We conclude that reference to landmarks is intended to help movers to construct a mental representation of an unfamiliar environment in advance and to prepare them cognitively to get through difficult or uncertain parts of that environment.