Chartreuse.

Located between Grenoble and Chambéry, the Chartreuse massif is crowned by summits like Chamechaude, the Dent de Crolles, and the Grand Som. Its accessibility inevitably makes it quite popular, but there are always lovely walks to be found for those seeking solitude. Its limestone geology is highly distinctive: you can walk along exposed ledges (the famous "sangles") and discover remarkable natural arches. It's also an ideal terrain for multi-day treks. The traverse of the Hauts de Chartreuse Nature Reserve is notably punctuated by charming alpine huts, the "haberts". It's also a reliable destination for winter walks.