The Alabama River runs along the north edge of downtown, and the city has done a decent job of opening up its frontage with a tiered amphitheatre, walking path, and an old-style riverboat (the Harriott II) offering daytime and dinner cruises. The 1898 Union Station, restored, anchors the walk at one end.
The Riverwalk is the natural place to end a downtown walking day — there's a pavilion, lawn space, and frequent free events in summer. The 2023 riverfront brawl that made national news happened on the dock here.