There is one average-sized nest visible from the parking lot of the Dusable Museum. My photos of this nest did not turn out very well but in the future expect better, more colorful pictures to replace the current ones.
Here it is: the single nest as it would look from the parking lot. Most people would mistake it for a squirrel's nest or just some bizarre clump of twigs suspended in a tree, until they see the bright green parakeets flitting around (disappointingly absent from this photo). The entrance holes on the underbelly of the nest are obscured by the shadows on this clowdy day.
When one views this nest from a closer vantage point, it looks the same. However, notice the two parakeets perched above the nest. The cloudy day obscured the color and scanning the photo absolutely ruined it. To the west lies a large field with trees at one end where the parakeets can commonly be observed grazing on the ground or perched in the trees. Undoubtedly the nearby Washington Park, which is rather large, is a favorite haunt of the birds at this site.
Here is a closeup of the picture above. Notice how the head of the parakeet is cocked, looking at the ground.