Durham cathedral is absolutely stunning, set in large grounds by the castle there is a large green to the front with café which serves lovely teas. There is no fee into the cathedral, it is donation, there is no photography allowed either, any miscreants are collared quickly by staff, this is despite parts of harry potter being filmed there, presumably they were paid. The stained glass windows are a marvel, what ever your views on religion are, the building is truly impressive. Don't forget to see Bedes tomb and that of St Cuthbert too. The colonnade with the bats flying around seemed to keep children happy. We didn't get up the staircase as it was closed at the time we visited.