On June 24, 1921, a group of children play what looks like ring–around-the-rosie at West Penn playground.  Next to them, a smaller group piled into a wagon faces the photographer.  It looks like most of the adults chose to stay in the shade.

In a photo taken from the opposite vantage point less than a year earlier, on July 22 1920, you can see that West Penn Park at that point was just a barren hillside.  That dirt track in the foreground is 30th Street.  And the smoke from the mills mostly obscures Downtown.

(Photos from the Historic Pittsburgh Image Archive)