Begun in 1173, the structure had started to list by the time the third storey was completed. According to some accounts, it was here that Pisa's most famous son, Galileo, disproved Aristotle's theories about the acceleration of falling objects by dropping different-sized balls from the belfry.
Believe it or not, the tower's real notoriety comes from its amazing slant. It is now nearly 15 feet out of plumb, and tilts a little more every year despite efforts to firm up the ground underneath.
The 294-step climb to the top is for the sturdy of limb. And only the strong-hearted should venture out onto the top loggia; at that point there is only a slender rail between you and the earth below.