During a visit to the City of David last week, I noticed that the Pool next to the Gihon Spring is being opened up for viewing. Scaffolding has been put inside the pool, apparently in preparation for the casting of a permanent concrete ceiling. The rocky southern edge of the pool is clearly visible, but there no remains of any wall built on that side could be detected.
In the initial reports it was claimed that a tower surrounded this pool. A reconstruction drawing on the site shows the Pool Tower to the left of the Spring Tower, a defensive tower built over the Gihon Spring. Both towers were accessed via a fortified passageway:
Although we have to wait for an official report, it appears that the pool was open on all sides, apart from the protective passage giving access to the waters of the pool at its northwest corner. The unprotected pool therefore must have been located inside the city walls. A larger area than was thought previously must have been added to the east of the original city.