Djelfa (Arabic: الجلفة, romanized: al-Ǧilfah) is the capital city of Djelfa Province, Algeria and the site of ancient city and former bishopric Fallaba, which remains a Latin catholic titular see.
It has a population of 490,248 (2018 census). The city lies at the junction of the N1 and the N46 roads.
The area is notable for its abundance of Neolithic rock carvings dating from 7000 to 5000 BC. North of Djelfa town there is an imposing physical feature known as Rocher de Sel (English: Salt Rock) that resulted from the erosion of rock salts and marls by rain. To the west of the town Megalithic funerary structures are found.