Caltanissetta is located on a hilly area in the upper valley of the Salso river, south of the San Giuliano Mount. The province has plenty of naturalistic sites such as the once larger Biviere lake, in Gela – today a favorite stop for migratory birds –, the lower valley of the Imera river – with archaeological and mining riches as well – the Soprano lake, the Sugherata wood in Niscemi and the valley of the Platani river. Since remote times the city of Gela with its renowned harbor has been an important outlet to the sea. The province can be divided into two large areas. The southern side, closer to the coast, comprises a number of considerably large cities, namely Gela, Niscemi, Riesi, Mazzarino and Sommartino; the northern, stretching inland, counts other fifteen cities.