surrounded by a green belt. Bielsko-Biała is enveloped by the Beskidy Mountains which are popular with winter sports fans. It offers over 150 ski lifts and 200 kilometres of ski routes. More and more slopes are illuminated and equipped with artificial snow generators. Szczyrk, Brenna, Wisła and Ustroń are the most popular winter mountain resorts. Rock climbing sites can be found in Jura Krakowsko-Czestochowska. The ruins of castles forming the Eagle Nests Trail are a famous attraction of the region. Often visited is the Black Madonna's Jasna Góra Sanctuary in Częstochowa – the annual destination of over 4 million pilgrims from all over the world. In the south-western part of the voivodeship are parks, palaces and old monasteries (Rudy Raciborskie, Wodzisław Śląski). Along the Oder River are interesting natural reserves and places for swimming during the summer. With its more than two centuries of industrial history, the region has a number of technical heritage memorials. These include narrow and standard gauge railways, coal and silver mines, and shafts and their equipment from the 19th and 20th centuries. Cities and towns Due to its industrial and urban nature, the voivodeship has many cities and large towns. Of Poland's 40 most-populous cities, 12 are in Silesian Voivodeship. 19 of the cities in the voivodeship have the legal status of city-county (see powiat). In all it has 24 cities and 47 towns, listed below in descending order of population (as of 2019): Economy The gross domestic product (GDP) of the province was 61 billion € in 2018, accounting for 12.3% of the Polish economic output. GDP per capita adjusted for purchasing power was 22,200 € or 74% of the EU27 average in the same year. The GDP per employee was 83% of the EU average. Silesia Voivodship is the province with the fourth highest GDP per capita in Poland. The Silesian voivodship is predominantly an industrial region. Most of the mining is derived from one of the world's largest bituminous coalfields of the Upper Silesian Industrial District () and the Rybnik Coal District () with its major cities Rybnik, Jastrzębie Zdrój, Żory and Wodzisław Śląski. Lead and zinc can be found near Bytom, Zawiercie and Tarnowskie Góry; iron ore and raw materials for building – near Częstochowa. The most important regional industries are: mining, iron, lead and zinc metallurgy, power industry, engineering, automobile, chemical, building materials and textile. In the past, the Silesian