The Kurpark is the spa-town side of Bad Hersfeld: lawns, trees, paths, and the old promise of mineral springs rather than abbey politics. It sits just west of the old town, so it is easy to add after the Stiftsruine rather than treating it as a separate excursion.
Come here for a breather, not for spectacle. The park works best as a soft ending to the old-town loop, especially if you have been walking between stone walls and half-timbered lanes all morning.