The Dutch Open Air Museum (Nederlands Openluchtmuseum) is a sprawling collection of historic buildings, workshops, and costumes from across the Netherlands, relocated to a parkland setting on the north side of Arnhem. Allow at least half a day.
Burgers' Zoo is more than a standard zoo. Its themed environments -- Burgers' Bush (a tropical rainforest), Burgers' Ocean (a coral reef aquarium), and Burgers' Desert -- are genuinely impressive. Located on the Schelmseweg, on the same road as the Open Air Museum.
Sonsbeek Park, right at the edge of the centre, is a beautiful English-landscape park with old trees, waterfalls, and a white villa that hosts art exhibitions. Good for a walk or a picnic.
The John Frost Bridge (John Frostbrug) over the Rhine is the rebuilt version of the bridge that British paratroopers fought to hold in September 1944. The bridge itself is unremarkable to look at, but walk across it once for the history.
For salsa fans, Dance Company Saltuya on the Korenmarkt offers courses, workshops, and shows.