a castle in Windsor. It is one of the official homes of the British king or queen. It was started by William I in the 11th century, and parts were added to it by several later kings and queens. Most of the present castle was either built or decorated in the early 19th century. Some of the rooms are open to the public when the king or queen is not staying there. In 1992 some parts of the castle were badly damaged by a fire, but these have now been repaired.