The palace was destroyed by the Nazis, but before that the Russians had taken samples of all the walls, wallpaper, wooden furniture, etc., etc., so they could reproduce it exactly after the war.
The Germans chose to believe that the russian were sub-human and not real Europeans. So even though Peterhof was considered a pearl in Europeran architecture they chose deliberately to destroy it, since it couldn't possibly be of any artistic value to their twisted minds.