There has been controversy about the real identity of the architect of the Leaning Tower of Pisa. For many years, the design was attributed to Guglielmo and
Bonanno Pisano,
[7] a well-known 12th-century resident artist of Pisa, famous for his
bronze casting, particularly in the
Pisa Duomo. Bonanno Pisano left Pisa in 1185 for
Monreale, Sicily, only to come back and die in his home town. A piece of cast with his name was discovered at the foot of the tower in 1820, but this may be related to the bronze door in the façade of the cathedral that was destroyed in 1595. However, recent studies
[8] seem to indicate
Diotisalvi as the original architect due to the time of construction and affinity with other Diotisalvi works, notably the bell tower of
San Nicola and the
Baptistery, both in Pisa. However, he usually signed his works and there is no signature by him in the bell tower which leads to further speculation
