The Venetian republic lasted from the late 7th century until its defeat by Napoleon in 1797. During this time, the leader and chief magistrate of the city was termed the Doge.
The Doge was elected for life by the citys aristocracy. The current Palace of the Doge was built between 1340 and 1565, being extended to the practical and political needs of the day.
The palace contains personal and state apartments as well as administrative offices of the Republic of Venice.
Don't be fooled by the relatively, for Venice, plain exterior, the inside of the palace / museum is spectacular.