 Groin vaults occur in early Romanesque buildings, notably at Speyer Cathedral where the high vault of about 1060 is the first employment in Romanesque architecture of this type of vault for a wide nave.In later buildings employing ribbed vaultings, groin vaults are most frequently used for the less visible and smaller vaults, particularly in crypts and aisles.A groin vault is almost always square in plan and is constructed of two barrel vaults intersecting at right angles.