Vitosha ( ), the ancient Scomius or Scombrus, is a mountain massif, on the outskirts of Sofia, the capital of Bulgaria. Vitosha is one of the symbols of Sofia and the closest site for hiking, alpinism and skiing. Convenient bus lines and rope ways render the mountain easily accessible. Vitosha has the outlines of an enormous dome. The territory of the mountain includes Vitosha nature park that encompasses the best known and most frequently visited parts. The foothills of Vitosha shelter resort quarters of Sofia; Knyazhevo quarter has mineral springs. Vitosha is the oldest nature park in the Balkans. The mountain emerged as a result of volcanic activity and has been subsequently shaped by the slow folding of the granite rock layers and a series of gradual uplifts of the area. It appears dome shaped at first sight, but the mountain, 19 km long by 17 km wide, actually consists of concentric denudational plateaus rising in tiers one above the other. Vitosha is separated into four main parts whose main ridges gather at a crown known as Cherni Vrah ('Black Peak', Bulgarian: ). This is the highest point of the mountain at 2290 m and is one of 12 peaks of Vitosha over 2000 m in height. It is the highest massif of Srednogorie mountain chain system, together with Sredna gora, Plana (mountain), Lyulin Mountain, Greben (mountain), Viskyar Mountain, etc. They all are a result of the folding of the earth layers through the Mesozoic, causing also magma sheet-like intrusion (or concordant pluton) that has been injected between layers of sedimentary rock. The laccolithic domed form of Vitosha is a typical example. Bulgaria's longest cave – Duhlata, with a total length of 18,200 m, is situated in Vitosha in the karstic region near the village of Bosnek. Since the ancient times of the Thracians a large population has always existed at the base of Vitosha. For the last four thousand years the economy of this large settlement has always been connected, in one way or another, with the neighboring mountain. The name Vitosha comes from the two-peaked, twin ridge mountain, which rises above the Sofia field and has acquired its present shape in stages over many millennia. A meteorological station was built at the top in 1935, and is still operating. The station also serves as a rest shelter for hikers and is the headquarters for the mountain rescue team.