The Argento trilogy is the Three Mothers, about three witches whose powers are rooted in their three homes in different cities:
Mother of Sighs; Freiberg (Susperia, 1977), a top 10 all-time horror movie
Mother of Darkness; New York City (Inferno, 1987), uneven but the best parts are excellent
Mother of Tears; Rome (The Mother of Tears, 2007), close to unwatchable. The reddit thread on this movie is titled "Dario Argento: W T F happened?"
The source material was Thomas de Quincey's Suspiria de Profundis, which is one of those wordy 19th century philosophic semi-pornographic collections that sounds like it was dictated while stoned to the gills probably because it was. What if Aleistair Crowley was your freshman roommate?