This beautiful marble tabernacle, showing the Madonna with Child Giving the Keys to St. Peter, is in eastern Castello on Fondamenta Quintavalle, on the way to the church of San Pietro di Castello. It’s an early 15th century work that was recently restored by the California chapter of Save Venice.
It's so wonderful seeing art outdoors as you roam around Venice, and there's actually quite a lot of it all over the city. You could make a case for moving works like this into a museum for protection, but instead, the restoration included adding lead to the roof to protect it from rain. I'm a bit sad that they finally had to move the four horses of San Marco inside, but those things are 2000 years old – it was time for them to get out of the weather, I think.