The Roman site of Tipasa, 70km west of Algiers along the coast road, is one of the most atmospheric ancient sites in North Africa. The ruins of the Roman town — basilicas, forum, theatre, mausoleum, baths — stretch along a clifftop above the Mediterranean. The sea is visible through the broken columns. In spring the ruins are carpeted with flowers.
Tipasa is manageable as a long day trip from Algiers — leave early, spend three or four hours at the site, and return for a late dinner. The drive along the coastal Corniche is itself pleasant. Entrance to the site is cheap and uncrowded by European standards. The small museum at the entrance has mosaics and sculpture from the site.