From 25 B.C. the Roman province of Africa comprised the whole of the region between the mouth of the Ampsaga (Wad Rummel, Wad el Kebir) on the west, and the two tumuli called the altars of the Philaeni, the immutable boundary between Tripolitana and Cyrenaica, on the east (Tissot ii.
The Kebir or Rummel - the river is known by both names - is formed by the union of several small streams south of Constantine, and flows past that town N.W.
The city occupies a romantic position on a rocky plateau, cut off on all sides save the west from the surrounding country by a beautiful ravine, through which the river Rummel flows.
The ravine, formed by the Rummel, through erosion of the limestone, varies greatly in width - at its narrowest part the cliffs are only 15 ft.
Along the north-eastern side of the city the Rummel is spanned in all four times by these natural stone arches or tunnels.