T.O.D.
Without a doubt, the soundtrack of BEN HUR.  I remember a school Christmas concert (when you could call it that), where the choir sang "Star of Bethlehem."  I couldn't for the life of me, figure out where I had heard that song before.  Once I got the soundtrack, it joined the OBC rotation.  It was the only soundtrack to get that honor until the LION IN WINTER soundtrack was released.