The chevet has been a good deal altered; most of the chapels remain, but the columns and arches round the choir have all been destroyed, or, at any rate, so covered over with modern work as to be no longer visible. A thirteenth-century chapel has been added on the north of the apse, and a small chapel of the fifteenth century and a large one of the Renaissance period on its south-west side. The other alterations are clearly indicated on the engraving of the ground-plan. [Illustration: No. 19 SANTIAGO CATHEDRAL. p. 152. INTERIOR OF SOUTH TRANSEPT, LOOKING NORTH-EAST] I have already said that the existing Renaissance steeples at the west end are built upon the lower portions of the original Romanesque towers. The only peculiarity about these is the planning of their staircases. The steps are carried all round the steeple in the thickness of the wall, and the central space is made use of for a succession of small chambers one over the other. These staircases are unusually wide and good, and their mode of construction is obviously very strong. The only other part of the church of the same age as the original fabric is the detached chapel to the north-east of it. This seems to have had originally no connexion whatever with the cathedral, the passage which now leads to its western doorway from the north transept being quite modern, and made for the reason already mentioned. Its western door is a good late Romanesque work, with shafts in the jambs, and carved capitals. The church itself consists of a nave and aisles of two bays in length, and a chancel with an aisle on either side. The columns are cylindrical, with carved capitals. The aisles have quadrant vaults, and the nave a semi-circular ceiling, but I could not ascertain certainly whether this was of plaster or stone. If the latter, then this little church affords a very interesting example of the adaptation of precisely the same mode of construction that we see in the great cathedral by its side, viz. the waggon-vault in the nave supported on either side by the quadrant vaults of the aisles. [Illustration: Central Shaft of Western Doorway.]