[Aelfwine]

With respect to he Rammas, the use of walls as a means of defense was a traditional tactic throughout history. The distance between the Rammas and the city is very unusual, but the sheer size of the Rammas is in keeping with the monolithic construction typical to Gondorians. I agree with Mark that the primary purpose was not (or should not have been) defense against invasion, but rather more generalized protection. I also agree that to attempt to hold the Rammas against Sauron's army was folly. It is not defensible in that sense.

The timing of the rebuilding of the bridge and its correspondence with the construction of the Rammas was likely coincidence. If the Rammas was intended as defense against invasion, which it probably wasn't, the reason was the fact that Gondor's population had fallen to the point where it needed something other than manpower to help. Becuase I believe that the people of Gondor did not have any confidence in the Rammas as a true mechanism of defense, I similarly do not believe that the rebuilding of the bridge was the product of such confidence. The bridge of Osgiliath was not directly defense-related. Rather it served the need to provide necessary and easy access to the east bank of Anduin for the citizens and military of Gondor.