Sec. 15. The foundations of the Saxon church at Peterborough present many difficulties, and may be of a later date than the foundation of the monastery in 655 A.D. But no such difficulties of date or plan exist with regard to the large Saxon church at Brixworth, between Northampton and Market Harborough. Its size and the fact that Roman material has been much re-used in its building have given rise to the tradition that it is a secular basilica applied to the purposes of a Christian church. As a matter of fact, the Roman brick-work has been re-used in obvious ignorance of Roman methods; so that this circumstance alone would make the legend improbable. The date of the building can hardly be earlier than about 680 A.D., when a monastery was founded here by a colony of monks from Peterborough. The plan originally consisted of (1) a western entrance porch, with a lofty western doorway, and smaller doorways on north and south; (2) a broad nave, divided from the aisles by arches, which spring from large square piers of plain brick-work; (3) a rectangular presbytery, divided from the nave by a screen-wall pierced with three arches; (4) an apsidal chancel, entered from the presbytery by a single arch. On each side of the chancel arch, a doorway entered into a narrow vaulted passage below the ground level, which probably formed an aisle round a crypt below the apse. At a later date, probably in the period of quiet following the later Danish invasions, the apse seems to have been rebuilt, polygonal externally, semi-circular on the inside, and the central crypt-chamber was then possibly filled up. The western porch was also used as the foundation for a tower, and the western arch blocked up with a filling containing a lower doorway, through which the circular turret for the tower-stair was entered. The aisles, either then or at a somewhat later date, having probably fallen into ruin, were removed. The clerestory of the nave remains, with unusually broad round-headed windows.