Jacula/Antonius Rex are Italian progressive rock pioneers that got their start in the late 60's. Their music consists mainly of church organ and electric guitar, with no drummer (even though there is some percussion in their music), and the lyrics are usually spoken (in Latin, I think). I have heard two of their albums and their songwriting is great, it sounds like church/funeral music or something you would hear in a horror movie or something like that. The real kicker here is that the guitar playing is very heavy and way ahead of its time, even compared to Black Sabbath, it sounds more like 80's black metal bands like Celtic Frost or Bathory. Oh, and they predated BS by a year with their first album "In Cauda Semper Stat Venenum", in 1969! Here are two songs from that album:
I'm still in doubt whether this was really recorded in 1969, these versions were remastered, but still... Whether the date is inaccurate or not, I enjoy the music, and look at that fucking album cover! Creepy as Hell...
And here's a song from their 1974 album, "Neque Semper Arcum Tendit Rex", for kicks: