The best aspect about Venezia is that everywhere in the historic city is a photogenic surprise, but there are two buildings that are worth entering, one of which is Palazzo Ducale.
Of course, what palace in Venezia is more extravagant than the ruling palace? Behind the ornate facade is the residence of the Doge, the ruling elder of the Venetian Republic. However, contrary to popular belief, the Venetian Doge was at best a figure head because the ruling powers actually were spread throughout many councils. Hence, Palazzo Ducale also hosts many offices for the many councils, with each room filled with beautiful paintings that fitted with the various themes!
Because of a devastating fire, Palazzo Ducale had to reconstructed - fortunately during the peak of both the Venetian wealth and talents. The result was the massive collaboration among stars like Titian and Veronese who filled every room with paintings and sculptures - some of which are so beautiful that each of them could easily be a headliner piece in any major art museum! Even if you speed through every room, you'll still be dazzled by the beauty and the extravagance that differ room by room. If you book the Doge's Apartment tour, you can see the private extravagance of the Doge residence.
However, the most impressive room has to be the main hall, Sala del Maggior Consiglio (Hall of the Great Council). Topped with Tintoretto's unbelievable "Last Judgement", this is Venezia's largest room, which is said to be hold up to 20000 noblemen who must convene every Sunday after a mass in San Marco! It is simply a true testament to the former greatness of the Serenissima Repubblica.
But don't leave Palazzo Ducale without seeing the gritty part of it. Cross the famous Ponte dei Sospori (Bridge of Sighs) and you will enter the much less glamorous prisons, which are certainly a far cry from the beauty that you just left behind. Let's just say the ruling Venetians were brutal, but if you want to see more, the Secret Itineraries tour that take you to the even more cruel prisons will satisfy you.
Anyway, the Institutional Rooms for the "vanilla" admission to Palazzo Ducale can easily take at least an hour to walk through and up to a whole day if you are truly into every masterpiece in this endless gallery! Regardless of how much time you have in Venezia though, this is a palace that you cannot miss!
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ENTERING PALAZZO DUCALE
The most basic admission is the combined San Marco Museum ticket for €19, which also includes the less-popular Museo Correr, Archaeological Museum, and Biblioteca Marciana. Unfortunately, you cannot buy only the Palazzo Ducale admission. Reduction for student or youth (through Rolling Venice Card) is available for €12 though.
Especially during high season, online booking via Venezia Unica or the official website is recommended so you can bypass the ticket office line.
If you wish to see more of Palazzo Ducale, considering booking through the official website either the Doge's Apartment or the Secret Itineraries (for more prisons) tour for exclusive access. Either tour will allow you to stay within Palazzo Ducale as long as you want afterwards.
The entrance is toward the lagoon, near Ponte dei Sospori.
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tl;dr version:
1) One of the only two must-enter buildings in Venezia
2) So many arts that it'll take forever to see!
3) See both the beautiful grandeur of the ruling chambers and the gritty darkness of the prisons
4) Book a tour to see the exclusive area read more