Here's a photo of the downtown from atop the Ascend Amphitheater hillside. Most of the trail is on the downtown side of the river, though it does cross over the Shelby Street bridge and continues to LP Field.
If you turn left off the access trail from Morgan park, you pass the cement company and soon climb atop the levee, with the river 20 feet or so below you on your right and commercial enterprises on the left. The trail is eight or so feet wide and paved, but don't lose your concentration -- it's a long way down and there are no guard rails.
In the photo below, the Greenway is the green line seen just below the blue river.
Other access points to the trail are at Riverfront Park (100 First Avenue North), Freehand Station (766 Freehand Road), 231 Great Circle Road, and 50 Titans Way near LP Field.