The flaw in work – the curvature – became noticeable at the very beginning. Then the deviation from the axis was only four centimeters. Because of the discovered defect, the construction dragged on for almost three hundred years. Many times there were talks about the demolition of the tower before the completion of construction. But the bell tower attracted the attention of visitors, so in 1350 it was decided to finish it. Finished an interesting project was risked by the architect Tomaso di Andrea.