B and I visited Mellon Square Park last fall while exploring the Pittsburgh area. We happened to be walking by and notice a sign for the park, so we embarked up the staircase that lead us to the landing where the actual park sits. I was so glad we stumbled upon this spot, as it was beautiful.
We didn't have a chance to spend much time here, as we were only walking through, but if I lived in the area I could see myself frequenting this spot. It's a lovely place to take a walk, or eat your lunch outside.