It would have been in 1970 at the Astor, long gone from Dominion Rd, that I first saw it.
We like to look back on those days, when licensed restaurants had barely been invented and we were still getting used to decimal currency, as a cultural dark age. But fans of non-mainstream films were actually quite well served.
The Lido, operated by Amalgamated Theatres, had a not-to-be-missed double feature every Sunday night - that was where I learned to love Bergman, Fellini, Truffaut, Antonioni (well, some Antonioni), Kurosawa and Louis Malle.
And the suburban cinemas played reruns of some of the great movies of the English-speaking world: I saw Bullitt at the Mayfair in Sandringham, Rosemary's Baby at the Capitol and In the Heat of the Night at the cinema in Kingsland whose name eludes me after all these years.
And at the Astor, which was somewhere near the Valley Rd lights, I first laid eyes on the lush, wild, hallucinatory and operatic western to end all westerns.
Italian director Sergio Leone had become known for his "spaghetti" westerns, produced in Europe and shot in Spain and starring a monsyllabic or entirely mute Clint Eastwood as the cheroot-chewing gunslinger in a poncho: A Fistful of Dollars, For A Few Dollars More and The Good, The Bad and the Ugly had arrived, like three gunshots in quick succession, in 1964, 65 and 66, but, trapped in school in Hamilton I'd missed them all.
So my first acquaintance with the genre was its apotheosis: the grand masterpiece called Once Upon A Time In The West.
To say it changed my life probably understates it. Here was a film that dared to cast Henry Fonda, Hollywood's ultimate good guy, as a psychopathic killer; a film in which the score was virtually a character; a film that simultaneously celebrated and subverted Howard Hawks and John Ford.
The wordless opening sequence (who can forget the fly in the gun barrel?) is alone worth the price of admission.
One of the great things about the film festival is the chance it gives you to relive peak moviegoing experiences or to acquaint yourself with old masterpieces.
(The screening yesterday of the 1929 landmark, Under the Southern Cross, with hilariously revisionist live music by Warren Maxwell, Maaka McGregor and Himiona Grace was a marvellous example of the latter).
That's why you'll find me at the Civic today, at 2.59pm, my heart beating fast as I anticipate the rise of the curtain.
If it was a live show, I'd be in the front row. Can't wait.