As can be seen in the spin synth, there is a construction on top of the tower. Those are walls and roof in the middle to protect the staircase from rain. So, one cannot stand in the middle to shoot for a standard pano. Also, the tower is big. I.e. some 10 meters from side to side. As one would not want the outer walls on the photos, but as much vertical coverage of the outside scenery as possible, one would move close to the outside wall to shoot over its edge. Note that the tower is square, which doesn't help moving around in a circle. Also, in tourist season it is crowded, which might make it impossible to get to the best positions.
With my then time Photosynth 1 understanding, I took photo sweeps at each side and corner adding up to a total of 58. This did work out reasonably for Photosynth 1 and unexpectedly fine for ICE. It did not for Photosynth 2. I have spent (a lot of) time to select 13 photos to get an as smooth as possible play in Photosynth 2.