It would seem that in those early days the south-western hill was not yet inhabited, or at any rate was not yet enclosed by a wall, although a garrisoned watch-tower stood upon it. The highest hills are not always deemed the best positions for a citadel or castle. It was not so at Athens, and it is not so in Edinburgh. The Jebusite population of Jerusalem was mostly clustered on the eastern hill. In 1879 Sir Charles Warren said: “The strongest point, to my mind, in favour of Ophel having been the ancient site of the Jebusite city is the fact of the one spring of water being found there. I have carefully noted the manner in which the Kaffirs have located themselves close to water in their various strongholds, and I think that unless there were very urgent reasons, the Jebusites would have located themselves near what is now called the Virgin’s Fountain.” But while the eastern hill was Zion,[33] the Akra was the stronghold of its owners and defenders, their castle occupying an advantageous promontory defended by valleys and ditches. A castle or fort so situated, could not, however, stand a siege, unless it possessed a secret supply of water; and Warren has spoken of the Virgin’s Fountain as the only spring. But there is some mystery about the _Hammam esh Shefa_, and many, including Warren himself, are inclined to believe it may be connected with a spring. The water is stated to be clear and free from the impurities of rain water, and the supply is never exhausted. The position of this “well” is in the Tyropœon Valley, in a line between Akra and the Dome of the Rock. The entrance to the fountain is by a narrow opening, but the shaft soon expands to about 12 feet square. At the bottom is an excavated chamber on one side, and a passage on the other. The passage expands into a vault, beyond which the channel becomes crooked and irregular. It appears that an ancient conduit enters the vault at the extremity of the horizontal passage, but its direction and source are unknown. May not some conduit have enabled the besieged garrison of the Akra fort to draw water from this source? A few years ago the Rev. F. W. Birch, arguing on the supposition that it was the city on Ophel which Joab captured for David, suggested that he found his way into it by the secret tunnels and shafts from the Virgin’s Fountain. That Ophel might be captured by surprise in that way seems likely; only it was not Ophel that Joab had to capture, but Akra. The Lower City had all been taken, except that the Akra held out still. If its garrison obtained water from the _Hammam esh Shefa_, may not Joab have effected an entrance from _that_ spring? He did not have to _get up to_ a “_gutter_,” nor yet to a “water course,” but to “reach them by the aqueduct” (_B’Tzinnor_).