Evocative Abstract / Architectural Vintage Snapshot

I think the subject here is the corner of the interior of a building, but it is the abstractness and ambiguity that make it interesting to me, all about form and shade and composition. (I'm really not entirely sure which end is up!) Both crisp and soft feeling, better in hand, glossy surface.

4 3/4" x 4", very good condition. C. 1960s-70s I would guess.