The GR 20 (or fra li monti) is a GR footpath that crosses the Mediterranean island of Corsica running approximately north-south, described by the outdoor writer Paddy Dillon as "one of the top trails in the world".
The whole trail is about 180 km long, clearly waymarked throughout, the walk for most people takes around 15 days. The trail is usually considered as two parts: the northern part, between Calenzana and Vizzavona and the southern part, between Vizzavona and Conca.
Vizzavona is considered the middle as there is a train station, and therefore is an accessible point for walkers beginning or ending a walk consisting of half the route. From Vizzavona, the train can be taken to Bastia or Ajaccio as well as many smaller towns and villages such as Corte. The northern part is considered by some the more difficult part, because of the steep and rocky paths, though this could be an effect of many walkers beginning in the north and not being as fit for this section. The southern part of the trail is often considered easier though the lower altitude may give rise to higher temperatures in summer and so provide more difficult walking conditions.
Along the trail there are mountain huts described as "refuges" or gîtes. The standard and price of accommodations and food varies from refuge to refuge. One can sleep in a tent near the refuge, but it is not permitted to pitch tents along the trail.
The GR 20 is an advanced trail. Of the less difficult but beautiful trails on the island two Mare e monti (from sea to mountain) and three Mare a mare (from sea to sea) trails are the best known.
Read more about GR 20: Route