I think it’s London Planetree, which the USDA plant database lists as “Platanus hybrida Brot. “, given that’s a very common tree in Pittsburgh. I am pretty sure this is not a native sycamore because the bark is green…American Sycamores generally have brown bark and the underlayer is gleaming white. Although I wouldn’t be able to identify an Oriental Planetree by sight since I’m not familiar enough with them.
Several of you have the right answer. This is the bark on one of Schenley Park’s London plane trees, planted in the late 1920′s. The scientific name of these trees is Platanus × acerifolia because they are a hybrid of the Oriental plane tree and the American sycamore. London Plane tree bark looks brown from a distance, American sycamores look white. This photo is too small to give you a good look at the whole tree so, yes, it’s a trick question.