Djelfa is the capital city of Djelfa Province, Algeria and the site of ancient city and former bishopric Fallaba, which remains a Latin catholic titul…Djelfa 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 520622. The city lies at the junction of the N1 and the N46 roads.