en.wikipedia.org/wiki/Densu%C8%99_Church
It was built with stones taken from the nearby roman city of Ulpia Traiana Sarmisegetuza, as well as from the old Dacian capital of Sarmisegetuza Regia.
Therefore, I do not believe it used to be a Roman temple before becoming a church, as stated in the wikipedia article (I don't think the Romans would use their own city as a quarry).
