Night-blooming cereus (grown from a cutting in the 1960s)

I grew this plant from a cutting off my grandmother's plant back when I was in junior high school. I realized this week that it therefore probably qualifies as one of the items I've owned for longest, so I figure the word "vintage" applies. It flowers once a year if I'm lucky and the flowers only open for one night. The rest of the year it's pretty much just a big, ugly plant. It was total luck that it flowered this week.