This palace looks like it’s floating in the river, but it’s stationary. Built with the water floating around it, it was actually used as a prison once.
Here’s a link to the Wikipedia article about it, but it’s in French so you may have to hit the translate button to read it.
At first I thought it was a church, but a quick search showed I was wrong.
I think you might enjoy reading about it as well as playing the jigsaw puzzle.

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