According to the legend, the name "Osogovo" originates from the Old German words "osso" (god) and "gov" (place), which means "a divine place". The powerful granite massif of crystal rocks, is about 110 km (68.35 mi) long and 50 km (31.07 mi) wide, with the highest peak being Ruen, at 2251 m. Osogovo or Osogovska Planina is a mountain and ski resort located between southwestern Bulgaria and northeastern Republic of Macedonia.
The steepest slope of the mountain is in the west, stretching down from Carev Vrv. Osogovo is the northernmost and highest part of the Osogovo-Belasica group and is situated between the Kyustendil and Kamenitsa Valleys, Dobro pole and Bregalnica and Kriva Reka river valleys. The west slopes are steep, while the southeast ones are slant, the mountain is rich in polymetal ores.There are many legends about the origin of the name Osogovo, but the most famous one is that it was given by the Saxon miners who were mining gold and silver in that region in the past.
Its volcanic relief is made of conic peaks and volcanic tuff. The diverse flora distinguishes vertical coverage: an under-mountainous zone up to 1000 m where trees like oak, elm, hornbeam, ash, hazel and others can be found; a mountainous zone (1000–1800 m) covered mostly with beech trees; and a sub-alpine zone covered with grass pastures and bushes of juniper trees.
The rivers and streams are a natural habitat for barbell, chub and mountain trout. Deciduous and coniferous forests dominate. The area is inhabited by rare Alpine Newt.
The nature and climate conditions allow for all-year tourism. Important towns at the foot of Osogovo are Kocani and Kriva Palanka to the west and southwest in the Republic of Macedonia.
Mountain lovers should be careful in the northern parts of the mountain, since there is a danger of avalanche. The climate in Osogovo is characterized by severe winters, heavy rains and thick snow cover.