GR 20, Long-distance trail in Corsica, France

The GR 20 is a long-distance footpath that runs roughly 180 kilometers (112 miles) through Corsica, linking the village of Calenzana in the north to Conca in the south. The route crosses alpine terrain with rock formations, narrow ridges and mountain passes, passing through several valleys between the island's highest peaks.

Volunteers led by Michel Fabrikant carried out the first waymarking of the route in 1970, when it received the number 20. The Comité national des Sentiers de grande randonnée homologated it in 1971, and the first two refuges, wooden chalets of the "chalouins" type, were built that same year. The trail opened along its full length in 1975.

The name Grande Randonnée refers to a French network of marked footpaths established since the 1940s. The red and white paint marks along the route follow a uniform system that helps walkers navigate through the mountains and keeps traditional paths visible.

The trail is divided into roughly 15 stages running between mountain huts that provide basic sleeping quarters and meals. Between June and September, booking huts in advance is advisable because spaces fill quickly during this period.

The full route accumulates about 12,000 metres of elevation gain, not a combined ascent and descent figure. The trail is waymarked throughout, and the two wooden chalets built as the first refuges in 1971 were of the "chalouins" type. Bivouac is only allowed in set zones near the refuges and on the Prati plateau below Monte Incudine.