Britain's least well-known royal palace and yet probably the most romantic, Edinburgh's Palace of Holyroodhouse sits in the shadow of the dormant volcano Arthur's Seat. It is also one of Britain's smallest palaces and yet events at Holyrood have determined the fate of three countries - England, France and Scotland. It was also the last place where a royal prince challenged the right of an English king to sit on the throne. Fiona Bruce discovers remarkable objects from the Royal Collection that are intimately bound to the Palace's turbulent history - from the spectacular Darnley Jewel with its many hidden messages to the cat-and-mouse needlework of a doomed queen.