Although the importance of landmarks for human navigation and for orientation is well accepted, most of today's navigation systems hardly incorporate any landmark information or information supporting orientation. Different from previous research that only addressed turn-by-turn instructions in verbal forms and landmarks at decision points, the present study provides empirical evidence that human-generated wayfinding instructions are not solely turn-by-turn but the majority of instructions provide orientation information. We propose a new classification scheme for identifying information in wayfinding instructions that will not only support orientation but also facilitate construction of mental map. We explored and compared two forms of representations-visual sketch map and verbal instructions. Results revealed that landmark information is important in human wayfinding instructions with particular importance of local landmarks along the route and global landmarks that support orientation. In addition, sketch maps contained more global landmarks than verbal instructions. In contrast to turn-by-turn navigation, we found that many instructions in human route descriptions do not always refer to turning actions but to orientation. We conducted interviews with a set of raters on what they consider helpful information in both forms of representations. These results confirmed our findings and supported that future route descriptions can be more meaningful and helpful when they are enriched with orientation information as they conform to how humans structure wayfinding instructions.