We bought the combined ticket for 6 euro - we visited both Acazaba and Colegiata. Church looks great from outside. Inside you can spend 5 - 10 minutes only. The most interesting thing for us was the sculpture of the half lady and half serpent. Other than that, the whole area is worth visiting -Alcazaba, Colegiata, and Arco de los Gigantes. All these places are next to each other.