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Outdoor chess tables
(lemmy.sdf.org)
There were ones near the Children's Museum, in the commons next to the big red corporate logo-y looking sculpture. But they were removed either last summer or the summer before. AFAIK, they won't be returning.
I have vague memories of seeing chess tables somewhere in the Allegheny Commons, maybe/probably the ones you're describing.
I'm going to be on the northside this afternoon. If I get there early enough, I may take a look around and see if any remain.