The Solvay Hut is a mountain hut located on the north-eastern ridge of the Matterhorn, near Zermatt in the canton of Valais in Switzerland. At 4,003 metres (13,133 ft), it is the highest mountain hut owned by the Swiss Alpine Club, but can be used only in case of emergency.
From a comment at TYWKIWDBI:
I remember visiting this hutte back in 1974 when I climbed the Matterhorn. It is about 2/3 of the way to the top! It’s kind of the last pause for the climbers before the really steep stuff at the top. That drop-off is no illusion!!