Mr. Prior in his "History of Gothic Art in England" tells us that two types of east end were to be found in the Anglo-Norman churches, both brought from the Continent, one the chevet prevalent in Northern France, the other derived originally from fourth and fifth century churches of the East, passing to Lombardy in the ninth century, and then along the Rhine and even reaching Normandy. Such was the original eastern termination of St. Stephen's, Caen; such may still be seen in St. Nicholas', Caen. This east end consisted of a number of parallel aisles, each with its own apse at its eastern end. "Norman use had squared the aisle endings of the choir two bays beyond the cross, the apse projecting its half circle beyond this, as at St. Etienne's, Caen, and in this form Lanfranc's Canterbury had been built."[4] [4] Prior's "History of Gothic Art in England," p. 63. In St. Albans this plan was further developed; from each arm of the transept two apses projected eastward, the outer ones consisting only of a semicircular projection from the transept, the inner ones of a rectangular bay from which the semicircular part ran eastward. The choir aisles, as we should now call them, consisted of four bays, beyond which they ended in a projection semicircular within, but rectangular when seen from the outside, the walls being thickened at the corners. These aisles were divided from the presbytery not by open arcading but by solid walls. The presbytery itself terminated in a semicircle projecting beyond the ends of the aisles. This extended as far as the centre of the present retro-choir. Above the crossing rose the central tower, much as we see it to-day, save that it was probably crowned with a pyramidal cap rising from its outside walls. Probably also the tower as well as the rest of the church was covered with whitewashed plaster, thus hiding the material of which it was built--the Roman bricks of which mention has been already made. These bricks surpass in hardness and durability those of modern days, and are of different size and shape from those we are acquainted with. Those used in St. Albans are of two sizes, 17 x 8 x 2 and 11 x 51/2 x 2. The joints are wide, the mortar between the courses being almost as thick as the bricks. The window jambs and the piers were built or faced with brick; even the staircases were of brick. What stone was used is clunch, from Tottenhoe in Bedfordshire, which, according to Lord Grimthorpe, is admirably suited for interior work, but absolutely worthless for exterior, as it decays very soon, and if it gets damp is shivered into powder by frost. [Illustration: THE SOUTH-WESTERN PORTAL, BEFORE THE REBUILDING OF THE WEST FRONT. From a drawing by W.S. Weatherley, in Sir G. Scott's "Lectures on Mediaeval Architecture." (By permission of Mr. John Murray.)]