The Trail d’Auffargis begins at the former Sablière site in Auffargis, a Yvelines village situated between Versailles and Rambouillet. ASR Trail 78 organizes the weekend, focusing on trail running within the Rambouillet forest and the Haute Vallée de Chevreuse Regional Park. The schedule features a 15 km night race, a 26 km short trail, and a longer trail approaching marathon distance, varying by edition. Participants can also opt for combined challenges linking the night race with either the short or long trail.
The event is primarily a forest run, with paths winding through trees over rolling terrain and sufficient climbs to make the distances demanding. The night race commences in the evening, while the longer Sunday races start in the morning, requiring participants in the challenge format to recover swiftly for the next day. The event has now exceeded a dozen editions, with results and race media managed by OXYBOL in recent years. Some listings also note a 10 km walk, offering an option for those seeking the forest environment without the longer trail races.