The third biggest city and a spectacle in the North, Constantine is a natural fortress created by the river Oued Rhumel which has carved out a deep gorge making it the perfect city for defense against intruders.
There is remarkably little to see, considering how long and interesting story the city has, but there is something special about the city. Its a bit like the flying Island in Gullivers Adventures and just walking though the old city and exploring the seven bridges was enough to keep me occupied for a day.
I didnt spend the night, but returned back to El Eulma. It did not seem like there were a lot of hotel options, so Constantine might be easiest to do as a day trip from Setif, El Eulma, Skikda or Guelma. Its not a place I would go back to, but a unique place that I am happy to have seen.