St. Mark's Basilica majestically symbolizes the lagoon and enshrines the city's history. Possession of the saint's relics enabled the Republic to establish its authority, from 828 onward, over Grado and Aquileia. In 1063, under Doge Domenico Contarini, it was decided to rebuild the church on the same Greek cross plan as the previous one.
In 1096 it was finished, but the decorative work continued until the beginning of the 19th century. The model had been furnished by the Church of the Holy Apostles in Constantinople (536-46); five domes covering the crossing and each of the arms, supported by large piers linked by arches. The light was thus directed towards the centre of the basilica, leaving the side aisles in comparative shadow.
The first patron saint of Venice was St.Teodoro. In 828 St.Mark the Evangelist substituted him when two merchants smuggled his mortal remains back from Alessandria (Egypt). St.Mark's remains were initially buried in a chapel in the Doge's Palace but later a church was built that was to be his perpetual resting place. The church later suffered damage from fire and was modified many times to adapt to Venice's evolution of power and wealth. This simple church evolved into St.Mark's Basilica. The modifications to the Basilica continued on through an entire century, therefore the results of the construction exhibit a mixture of different styles.
In order to justify the theft of St.Mark's body, legend states that when the Evangelist went to the lagoon, an angel came and said: "Pax tibi Marce, Evangelista meus" (Translation from Latin : peace to you, Mark my Evangelist), showing in this way that God had determined Venice as the final resting place of the Saint. The Venetians acted to fulfill the divine profecy.
St.Mark's Basilica is also well known for the Pala d'Oro, one of the richest and most precious altar screens in the world. It is covered with more than 3000 precious stones and enamel ikons inlaid in gold.