Not an Argento rip - off!
I've seen it described as such, but this film can't be a rip off of "Suspiria", because it was made in 1969, and "Suspiria" was made in 1977.
I bet Argento watched it though - the baroque school, the mysterious atmosphere, the murders, it all seems very similar.
"Suspiria" is a classic of course, but "La Residencia" is also very effective. The murders are brilliant! The one in the greenhouse, all that slow motion is wonderful. And the building it's filmed in has to be real - it's gorgeous.
Mind you, the ending is so crazed it almost seems like they changed their minds in the last 10 minutes and decided to make a different type of film entirely!