Nowadays, navigation systems are widely used to find the shortest path between a starting point and a destination. In order to guide the user these systems rely on visual information. However, consider, e.g., visually impaired or elderly people. They may not be able to navigate using only visual information. Additionally, sometimes there is no visual information (i.e., visual landmark) available. In such a case olfactory information could be a helpful route guidance. To identify possible olfactory cues, we performed two online studies as well as a focus-group interview and identified 13 different smell classes usable for navigation and wayfinding. Based on our results, we\end{Evarev} gathered data for these classes in an urban environment. We collected 201 smells and mapped their values for the properties temporary, intensity, and notes. We underline the findings of previous studies that the majority of odours in an urban area are gastronomy and waste related odours. We find a number of smells that have daily or seasonal dependencies and conclude that the temporary property should be captured in more detail in future studies. We also discuss additional properties of smells and smell mapping that should be considered in future work.