The Tour du Mont Blanc or TMB is one of the most popular long-distance walks in Europe. It circles the Mont Blanc massif, covering a distance of roughly with of ascent/descent and passing through parts of Switzerland, Italy and France. It is considered one of the classic long-distance hiking trails. The circular route is normally walked in a counter-clockwise direction in 9-14 days. It is also the route of an annual mountain marathon in which the winners normally cover the entire distance in less than 26 (women's race) or 20 hours (men's race). Route Usual start points are Les Houches in the Chamonix valley or Les Contamines in the Montjoie valley (in France), Courmayeur from the Italian side, and either Champex or a point near Martigny in Switzerland. The route passes through seven valleys around the Mont-Blanc massif, an anti-clockwise start in Chamonix would lead through the Chamonix (or Arve) valley, then Montjoie, Vallée des Glaciers, Italian Val Veni, Val Ferret, Swiss Val Ferret, and either the Arpette or Trient valley in Switzerland, dependent on the route chosen. The "official" route has changed over the course of the years and many alternatives, or "variantes", exist to the standard route. Some can take an intrepid walker onto paths requiring greater fitness, awareness and skill. Others provide less demanding options, which are often quicker than the accepted route, but provide lesser viewpoints onto the mountain ranges. For a part of the way, between the summit of Brevent and the Col de la Croix du Bonhomme, the route coincides with the European long-distance footpath GR5 as it makes its way from the North Sea to the Mediterranean Sea. A link can also be made with the walkers' Haute Route from Chamonix to Zermatt in the Swiss Alps. The highest points on any variant of the trail are the Col des Fours in France and the Fenêtre d'Arpette in Switzerland, both at an altitude of . This is not high enough to cause altitude sickness for most people, nevertheless the trail provides a tough physical challenge. Experience of walking in mountain country is vital and, because mountain weather can change very rapidly, participants on the Tour du Mont Blanc should be suitably equipped. Plentiful accommodation exists along the entire route, allowing it to be broken into segments to suit any fit person. This takes a variety of forms, from separate bedrooms to large mixed-sex