Analysis of information sources in references of the Wikipedia article "कोरदोबा की मस्जिद-गिरजा" in Hindi language version.
The church is Catholic and has been for centuries, but when Catholic Spaniards expelled the local Arabic and Muslim population (the people they called the Moors) in 1236, they didn't do what the Catholic Church tended to do everywhere else when it moved in and displaced locally held religious beliefs: they didn't destroy the local religious shrine and build a cathedral of the foundations of the sacred space that had been knocked down. Instead, they built a church inside and up through the roof of the mosque, and then dedicated the entire space to Our Lady of the Assumption and made it the cathedral for the Diocese of Cordoba.
