The Italian Alps are divided into three main groups. The first group, the Western Alps run north to south from Aosta to the Cadibona Pass, with the highest peaks of Mount Viso 3,841 metres and Gran Paradiso 4,061 metres. This group is regarded as the highest mountain completely within Italy. The second group, the Central Alps run west to east from the Western Alps to the Brenner Pass, leading into Austria and the Trentino Alto Adige valley. This group also has high peaks, such as Monte Bianco (Mont Blanc) with a summit of 4,807 metres just over the border in France, Monte Cervino (Matterhorn) 4,478 metres, Monte Rosa with a summit of 4,634 metres just over the border in Switzerland, and Mount Ortles 3,905 metres. The last group, the Eastern Alps run west to east from the Brenner Pass to Trieste and include the Dolomites and Monte Marmolada 3,343 metres. The Italian foothills of the Alps, which reach no higher than 2,500 metres, lie between these great ranges and the Po valley.