The excellences or defects of a building are more due to the shape and size of its floor and, incidentally, of the walls and columns or piers which inclose and subdivide its floor than to anything else whatever. A map of the floor and walls (usually showing also the position of the doors and windows), is known as a plan, but by a pardonable figure of speech the plan of a building is often understood to mean the shape and size and arrangement of its floor and walls themselves, instead of simply the drawing representing them. It is in this sense that the word plan will be used in this volume. The plan of a Gothic Cathedral has been described, and it has been already remarked that before the Gothic period had commenced the dimensions of great churches had been very much increased. The generally received disposition of the parts of a church had indeed been already settled or nearly so. There were consequently few radical alterations in church plans during the Gothic period. One, however, took place in England in the abandonment of the apse. At first the apsidal east end, common in the Norman times, was retained. For example, it is found at Canterbury, where the choir and transept are transitional, having been begun soon after 1174 and completed about 1184; but the eastern end of Chichester, which belongs to the same period (the transition), displays the square east end, and this termination was almost invariably preferred in our country after the twelfth century. A great amount of regularity marks the plans of those great churches which had vaulted roofs, as will be readily understood when it is remembered that the vaults were divided into equal and similar compartments, and that the points of support had to be placed with corresponding regularity. Where, however, some controlling cause of this nature was not at work much picturesque irregularity prevailed in the planning of English Gothic buildings of all periods. The plans of our Cathedrals are noted for their great length in proportion to their width, for the considerable length given to the transepts, and for the occurrence in many cases (_e.g._ Salisbury, thirteenth century) of a second transept. The principal alterations which took place in plan as time went on originated in the desire to concentrate material as much as possible on points of support, leaving the walls between them thin and the openings wide, and in the use of flying buttresses, the feet of which occupy a considerable space outside the main walls of the church. The plans of piers and columns also underwent the alterations which will be presently described.[8] Buildings of a circular shape on plan are very rare, but octagonal ones are not uncommon. The finest chapter-houses attached to our Cathedrals are octagons, with a central pier to carry the vaulting. On the whole, play of shape on plan was less cultivated in England than in some continental countries.