Here we see the magnificent "Big Tower' of the Castle. The Royal Standard is always flown when HM The Queen is in residence.
Above the main door of this tower is a carving of the Order of the Thistle or the Knights of St Andrew; The Royal Arms of Scotland. This was founded in 1540 by King James V and was created by him, for himself and 12 knights, reflecting Christ and the 12 apostles. A flag showing The Royal Arms of Scotland is flown when HM The Queen is not in residence.
Much fascinating information is contained in the following video.