 Although the actual number of documents housed in the present archive of the Congregation for the Doctrine of the Faith is not known because documents dated after Pope Leo XIII's death, in 1903, are still closed to researchers, there are known to be 4,500 documents available to scholars up to that point.Over the years, there have been numerous important documents placed by various Popes in this archive.Probably the best known case is the 1944 and 1957 revelations by Fatima seer Lúcia dos Santos, but there exist numerous other documents of this type placed in the archives whose content was partially known before being placed there.