In considering the original form of the church there is yet another important point to be noted. It will be seen from the plan that at the ground level the central area is not cruciform, but is rather an oblong from east to west with large arches on the north and south sides. This oblong is, however, reduced to a square at the dome level by arches thrown across the east and west ends, and this, in conjunction with the setting back of the dome arches already mentioned, produces a cruciform plan at the springing level. The oblong character of the central area is characteristic of the domed basilica and distinguishes this church from S. Andrew or S. Mary Panachrantos. The employment of barrel vaults in the ambulatory is also a point of resemblance to the domed basilica type, though the cross groin is used on the angles.[246] In this feature S. Mary Pammakaristos resembles S. Andrew and differs from S. Mary Panachrantos. We are probably justified in restoring triple arcades in all the three lower arches similar to the triple arcade which still remains in S. Andrew. The present arches do not fit, and are evidently later alterations for the purpose of gaining internal space as at the Panachrantos. The hexagonal piers between the ambulatory and the inner narthex are not original, as is evident from the clumsy manner in which the vaulting descends on to them. They are the remains of the old western external wall of the church left over when it was pierced through, probably in Turkish times, to include the narthex in the interior area of the building. The piers between the ambulatory and the gallery on the north side of the church also seem to be due to openings made for a similar reason in the old northern wall of the church when that gallery was added in Byzantine days. The dotted lines on the plan show the original form of the piers and wall, as shown by the outline of the vault springings above. The inner narthex is later than the central church and is of inferior workmanship. The restored plan shows the probable form of the church at that date. The outer narthex was added at a subsequent period.