Chamonix’s famous Cosmique Arete was first climbed by George and Maxwell Finched in August 1911.
From Summit Post:
The Cosmiques Ridge is a supurb varied route which is justifiably popular. It is the perfect introduction to Alpine mixed climbing has enough variety to keep experienced climbers happy. The route is also known as the Cosmiques Arête and South-South-West Ridge. It’s graded at AD (sometimes even PD or PD+) but the crux is hard for its grade and suitable mixed climbing and abseiling skills are required. Much of the ridge can be climbed moving together. The rock is excellent quality throughout and there are plenty of locations to place protection.
It is possible to climb the ridge year round however poor snow conditions will make the route more difficult and dangerous. In poor conditions, descending from the cable station down to the Col du Midi can also be a nervous affair. Most people climb the route between June and September.