Balkan Mountains, mountain range, south-eastern Europe, on the Balkan Peninsula, forming a continuation of the Carpathian system. The Balkan Mountains may be considered to begin at the western extremity of the Transylvanian Alps (see Transylvania), at the gorge known as the Iron Gate of the Danube, on the border between Serbia and Romania. Bounded on the west by the basin of the Morava River, the mountains form part of the border between Bulgaria and the Former Yugoslav Republic of Macedonia, and turn east across the centre of Bulgaria, extending for about 560 km (350 mi) towards the Black Sea. The range varies in width from 19 to 32 km (12 to 20 mi).

The average height of the Balkans is about 900 m (3,000 ft) above sea level; the highest point, Botev Peak, in central Bulgaria, rises to 2,376 m (7,795 ft). Several other ranges, including the Rhodope, extend south from the Balkans to the Aegean Sea. The principal pass of the range is the Shipka, at an elevation of 1,326 m (4,350 ft). A monument at the pass commemorates the Russian soldiers and the Bulgarians who fought back Turkish troops during the Russo-Turkish Wars.

The range is also crossed by roads, railways, and the Iskŭr River. The northern slopes of the Balkan Mountains drop gradually to form the Bulgarian Plateau, which ends at the Danube. The ancient city of Veliko Tŭrnovo spills down from the foothills to the Yantra River. On the south side, Sofia, the capital of Bulgaria, lies on an elevated plain at the foot of the mountains.

The Balkan range is composed largely of folded sedimentary strata of limestone and sandstone rock with crystalline schists. Resources include deposits of lignite and other coal, graphite, copper, lead, zinc, and iron; mineral springs with therapeutic properties; and coniferous and deciduous forests.