You may see Cathedrale du Sacre Coeur in the skyline before you actually find this grand building. Look around inside if the doors are open or just admire the facade from outside.
You'll find this principal church in Sidi MHamed. If you're vacationing on a budget, you'll be pleased to hear it's free to visit. Once you've explored Cathedrale du Sacre Coeur, head for other attractions in the area. Casbah, Algeria National Library and Great Mosque of Algiers will keep you busy.