It's worth a wander around and contains a church, war monument with eternal flame, a reasonable art museum and impressive views along the Volga River. Also you can take a walk atop (inside) the Kremlin's wall in summer (roughly from May to October), the entrance is by the stairs set a bit off the wall inside the Kremlin near the main entrance via Dmitrievskaya tower, the latter being one of Nizhny Novgorod's symbols.