Knock ( An Cnoc in Irish , meaning The Hill -- but now more generally known in Irish as Cnoc Mhuire , `` Hill of ( the Virgin ) Mary '' ) is a small town in County Mayo in Ireland . Knock 's notability comes from the Apparition of 1879 . Knock ( , meaning The Hill â `` but now more generally known in Irish as Cnoc Mhuire , `` Hill of ( the Virgin ) Mary '' ) is a small town in County Mayo , Ireland whose notability derives from the Knock Shrine where it is claimed the Virgin Mary , together with St Joseph and St John the Evangelist , appeared in 1879 .