NB - this is nowhere near Bolton, Lancashire!
Bolton Castle is a 14th century fortress built on a grand scale by Sir Richard le Scrope - whose descendents still own the place. Mary, Queen of Scots, was held here for 6 months and was allowed to use the time hunting and learning English. It was besieged, and badly damaged, by Parliamentary forces during the English Civil War, but is still remarkably intact and well worth a visit. Great views of the Yorkshire Dales from the battlements. Pleasant medieval gardens. The adjacent chapel of St Oswald and the village of Castle Bolton are both charming.
Warning: Bolton Castle is used as a wedding venue - check it is open to visitors before making a special trip.