One day in Norwich with grandmother

Hello everyone, me and my grandmother are visiting for a day trip this Saturday. Are there any recommendations for places to eat or things to do? We love history and old buildings. Maybe a nice welcoming pub? We will be visiting the castle and cathedral if open. I’ve checked the sub and it is full of cocktails and party spots, but that isn’t quite what I’m looking for. She is pretty mobile and we will be coming up by train from Suffolk. Tia!