This picture makes it look like going up the tower is at least doable. The others made it look like the only way to get up would be by hanging from straps attached to the ceiling, like on a subway.
And, this picture made me curious enough to want to find out what the Leaning Tower of Pisa is actually for, because I never knew. It turns out, according to Wikipedia, that it is a free-standing bell tower for Pisa Cathedral. The plaza where it is located also contains the cathedral, the baptistry, and the monumental cemetery, all very old and fancy-schmancy. Wikipedia says that the tower leans because of soft ground that couldn't support the weight. I think the tower is actually just jealous, because here we can clearly see that the tower is photo-bombing the cathedral: