It is difficult for us today to grasp the location and nature of the various landmarks Nehemiah mentions. The eastern wall ran (relatively) north-south, but the Ophel wall (filling in the gap between two outcropping points in this steep wall) may have had a (somewhat) east-west inclination at some point. In that understanding, the implication is that the Tekoites repaired the wall to that east-west point.
27 After him the Tekoites repaired another section opposite the great projecting tower as far as the wall of Ophel.