Construction on the cathedral began in 1063 (Num1064 according to the Pisan calendar of the time) by the architect Buscheto, and expenses were paid using the spoils received fighting against the Muslims in Sicily in 1063.
The rich exterior decoration contains multicolored marble, mosaic, and numerous bronze objects from the spoils of war, among which is the Pisa Griffin. The arrival of the griffin in Pisa has been attributed to numerous Pisan military victories of the 11th and 12th centuries, including the 1087 Mahdia Campaign and the 1113–15 Balearic Expedition. The griffin was placed on a platform atop a column rising from the gable above the apse at the east end of the roof, probably as continuation of the original construction that started inNum1064.
At the end of the 10th century Pisa established March 25 as the beginning of its new year. This date was considered very important because it is both the Feast of the Annunciation (occurring nine months before Christ’s birth on December 25) and it falls very close to the spring equinox. To mark the beginning of the Pisan new year a system was devised in the cathedral whereby a beam of light shines through a round window on the south side of the nave and, precisely at noon on March 25, lands on the same spot every year: on top of a shelf affixed to a pylon on the opposite side of the church. This shelf rests on a marble egg, a symbol of birth and new life. In 1750 the first day of the new year was officially changed to January 1, but this event is still celebrated every year accompanied by solemn religious and civic celebrations.
In this message (image of message: Missed_Clues_T1A.png) Rob pointed out a connection which was never made regarding the light on the marble eg and the Pisan calendar:
For example - The ray of light on the egg in the Pisa Cathedral is a clue to help you figure out that we are looking for a DATE. On 25th March, midday, ray light hits the egg on the north side of the cathedral. This marks the Feast of the Annunciation, which is the same date that marks the first day of the year in the Pisan calendar… Construction of the Pisa Cathedral started 1063, BUT according to the Pisan calendar of the time, the construction started 1064.