Some of the world's finest castles and palaces have seen more than their fair share of turbulent history, from warfare to domestic and political dramas. Many of them also hide fascinating secrets within – and sometimes underneath – their towers, walls and turrets. We've uncovered the surprising and often strange stories harboured by incredible castles and palaces around the world, including a royal zoo, the world's largest dolls' house and a daring escape helped by a wheel of cheese...