I'll be visiting relatives near Hadrian's Wall (which we have visited often in the past) between Christmas and the New Year when 2 of my daughters will celebrate their birthdays (they'll be 10 and 7). Any suggestions for a great day out for Harry Potter fans who are tom-boyish and like history-they like knights/ castles/ climbing/swimming. We are coming from Ireland so have lots of long walks in wild places at home and Alnwick castle is closed.