 The simplest type of vaulted roof is the barrel vault in which a single arched surface extends from wall to wall, the length of the space to be vaulted, for example, the nave of a church.An important example, which retains Medieval paintings, is the vault of Saint-Savin-sur-Gartempe, France, of the early 12th century.However, the barrel vault generally required the support of solid walls, or walls in which the windows were very small.