This trail along the Inner Harbor basically winds around the famous Baltimore Aquarium. It is mostly brick, but when you go behind the aquarium itself, that part is concrete. In addition, there are two pedestrian bridges that you cross over.
This is a great early morning outing that keeps you out of the shopping areas in the Inner Harbor. Obviously, you have fantastic views of the Inner Harbor, with plenty of places to rest, grab a drink or just say forget it and get some food!
If you are staying in Baltimore, this is a great way to see this part of the city.