This is important to note because it is the defense used by apologists for the "desecration" of the mosque in order to build the cathedral. It could be argued that because there was originally a church here, the mosque is the violation. Apparently the Visigothic era church was actually purchased by Prince Abd al-Rahman from his Christian subjects. He then leveled it and built the mosque. This was technically a legal transaction rather than raw conquest, but that's debatable. Little ruins of the Visigothic church are on display here.