When they at length arrived opposite the mound, Rejeb turned abruptly to the right and pushed through a clump of reeds on to a narrow stone causeway, fringed on both sides with tall rushes which completely hid it from view. It led directly to the mound, almost half a mile ahead in a straight line. Burnet learnt, later on, that the causeway was believed to date from the Babylonian age; it was supposed to have been built, not for the passage of the swamp--for in those days the surrounding country was probably dry land, carefully irrigated from the wadys--but as a means of access to the temple which then crowned the mound, in times of flood due to abnormal rainfall. Centuries of neglect had turned the land once well drained into permanent swamp, but the solid masonry of the causeway had withstood the ravages of time, though when Rejeb's people first discovered it it had been much overgrown with rampant vegetation. They had at once perceived the advantages of the mound as a natural fortress and of the causeway as the only means of access. They cleared away the overgrowth except at the edges, where the vegetation that was allowed to remain made the causeway a sort of secret lane. On riding up the mound, Burnet saw that the ruins were even more extensive than they had appeared at a distance. They covered a space nearly half a mile long and a third of a mile wide. He conjectured that the place had been the site of a temple and the dwellings of a community of priests. The lower part of what had once been a large tower was in a fair state of preservation, and dominated the rest of the ruins. It was here that Rejeb and his family were lodged; for, young as he was, he had already a wife and children. No other buildings had been habitable when the mound was chosen as a harbour of refuge; but the young men of the tribe had made for themselves fairly serviceable shelters out of the fragments of masonry with which the site abounded.