There isn't much there, but you can spend a good hour looking around the Amphitheatre and looking at the videos of the church that once stood there. The place is well restored and work is ongoing. Very cheap also. It cost only 3 euros for the family and cheaper still if you get a pass for all the monuments in Tarragona. There is no snack bar or drinks on sale, so take water if it is hot. The guides are very helpful and only too happy to give you a personal tour.