Suspiria (1977)

Suzy Bannion travels to Germany to perfect her ballet skills. She arrives at the Tanz dance academy in the pouring rain and is refused admission after another woman is seen fleeing the school. She returns the next morning and this time is let in. She learns that the young woman she saw fleeing the previous evening, Pat Hingle, has been found dead. Strange things soon begin to occur. Suzy becomes ill and is put on a special diet; the school becomes infested with maggots; odd sounds abound; and Daniel, the pianist, is killed by his own dog. A bit of research indicates that the ballet school was once a witches' coven, and as Suzy learns, still is.

IMDb: https://www.imdb.com/title/tt0076786