How does George Bernard Shaw use imagery in Saint Joan?

Saint Joan is set in France in the period 1429-1431, with an epilogue set in 1456. Four of the scenes are set in castles in the northern part of the country, including the castle occupied by the court of the Dauphin in Chinon and the castle in Rouen where Joan's trial takes place. One scene takes place in the cathedral at Rheims where Charles is crowned, another takes place on the banks of the Loire River in the French military camp across from Orleans, and one (the so-called Tent Scene) takes place in a tent in the English camp.