Some dramatic events have taken place at Windsor Castle, which was built more than 900 years, guided by Edward III and his obsession with tales of Camelot. There is a look at one of the most popular exhibits at Windsor - Queen Mary's Dolls' House - and Kate Williams revisits some of the castle's darker times, including the year when bubonic plague caused Queen Elizabeth to isolate at Windsor, and the death of Prince Albert in 1861.