In this paper we propose a highly detailed map for the field of autonomous driving. We introduce the notion of lanelets to represent the drivable environment under both geometrical and topological aspects. Lanelets are atomic, interconnected drivable road segments which may carry additional data to describe the static environment. We describe the map specification, an example creation process as well as the access library libLanelet which is available for download. Based on the map, we briefly describe our behavioural layer (which we call behaviour generation) which is heavily exploiting the proposed map structure. Both contributions have been used throughout the autonomous journey of the Mercedes Benz S 500 Intelligent Drive following the Bertha Benz Memorial Route in summer 2013.