The Tower of Pisa is the bell tower of the Cathedral.

Its construction began in the august of 1173 and continued (with two long interruptions) for about two hundred years, in full fidelity to the original project, whose architect is still uncertain. In the past it was widely believed that the inclination of the Tower was part of the project ever since its beginning, but now we know that it is not so.

The Tower was designed to be "vertical" (and even if it did not lean it would still be one of the most remarkable bell towers in Europe), and started to incline during its construction. Both because of its inclination, and its beauty, from 1...