When Medieval Europeans decided to build massive stone cathedrals, they had to use more complicated ... light blue in model B); and one with a diamond-shaped keystone (the Gothic arch, model C).

The Cathedral of St Etienne of Bourges, built between the late 12th and late 13th centuries, is one of the great masterpieces of Gothic art and is admired for its proportions and the unity of its ...

When Medieval Europeans decided to build massive stone cathedrals, they had to use more complicated ... light blue in model B); and one with a diamond-shaped keystone (the Gothic arch, model C).