Kasbah of Algiers is the best attraction of Algeria. The lower Casbah is mainly impressive by the french style houses with arcades for numerous small shops. The upper Casbah is more or less original with arabian roots architecture. Follow the stairs to get there, but do not become lost in the maze. You'll reach the fort, which is also named Kasbah. But since it is to be renewd, you'll will just pass by, probably.