Question: Refuge Robert Blanc is a refuge in the Alps located on the route of a popular walk that is roughly how long?
Sentence (from "Grands Mulets Hut"): If the state of the glacier is not too severe, the hut is wardened in summer and can be used as an alternative route of ascent to the summit of Mont Blanc, following the original historic route by the first ascensionists.
Relevant evidence: No