The Oude Haven area, near the Overblaak development and the Blaak train, metro and tram station, preserves the oldest part of the harbour, some of which dates from the 14th century. It's a decent place for a stroll, especially if you pause at one of the waterside cafes.
Check out the Openlucht Binnenvaart Museum , which has a collection of historic inland waterway boats that fills much of the basin. Restorations are ongoing; sit on a shady wall and watch.