On 22 February 1965, Walter Bonatti successfully completed one of the greatest feats in mountaineering: the first solo ascent of the north face of the Matterhorn. To this day, his ascent has been repeated only a few times (5) due to its enormous technical difficulty, rated ED+. It took Bonatti 5 days to complete the ascent (he set off on 18 February), spending 4 nights bivouacking in one of the most inhospitable places on earth.