The province of Caltanissetta is known for its hilly terrain made of peaks and valleys and also for the quantity of castles to be found throughout the region. The River Salso runs over this terrain. The main town of Caltanissetta is thought to have been inhabited as far back as prehistoric times but the city itself is thought to have started to take form during the Greek colonisation of Sicily.
Such a great range of settlements have left a wealth of archaeological evidence including objects which are housed in the region's museums and also archaeological sites surrounding the city including that of Sabucina. The Castle of Pietrarossa (Red Stone) which stands at the edge of the city is thought to have given the town its name as it was the original fort which protected the town. The original Carthaginian name was Castra Nicia (Fort Nicia) after Admiral Nicia of Hamilcar. All that remains of the castle is a tower which looks over the River Salso.
The town of Gela is actually more populated than that of Caltanissetta and is situated at the edge of the Mediterranean Sea. There is an Acropolis here which, until 405 BC, housed the town's main sacred buildings including a Doric style temple.