The natural lines of defence, and the position of the streets and gates, have thus been considered without any reference to literary statements. As to the upper city there is a general consensus of opinion, and the scarps on which the ancient walls stood have been examined, both here and on the Ophel spur farther east. It is on the north that differences of opinion arise, according as the writer accepts the traditional site of Calvary, and endeavours to show that it might have been outside the city, or, on the other hand, disregards this hampering condition, and relies on the ascertained levels of the hills and valleys. The present writer feels no hesitation in concluding that rocks on which he has so often set his feet, whether on the surface or deep down in the great tanks of the Hospice of St. John, cannot be removed, nor valleys which--though much shallower than of old--are still traceable inside the city be exalted, on account of the mistake which Bishop Macarius made as to Calvary in the fourth century. If there were any indication that Christians preserved the traditional site in earlier times, due respect should be paid to such indication. But we do not even know for certain that there were any Christians at Jerusalem till the third century, or about 170 years after the great destruction by Titus, and none of the Christian Fathers before about 330 A. D. show any acquaintance with Jerusalem topography, or mention any tradition as to the situation of Calvary. Fortresses are built on hills, not under them, unless when a citadel is occupied, with outer walls on the slopes. Ancient walls do not run in deep ravines, leaving a commanding ridge just outside. It is on these principles that we may most safely rest in considering the walls of Jerusalem.