The Palace of Shadow is a location in Paper Mario: The Thousand-Year Door. It serves as the main setting for Chapter 8 and is the last area that is explored in the game.
There is only one way to enter the palace, through the Thousand-Year Door. Only when Mario has the Map and the seven Crystal Stars will the door open. Within this area is where many dangerous traps and enemies are found. Some rooms contain trap doors, some contain many spikes, others are filled with deadly enemies like Dry Bones or Chain Chomps. There is also a Riddle Tower within the large palace that has eight different puzzles in which Mario must solve. After some heavy battles with Sir Grodus and Bowser, Mario must fight the final boss, the Shadow Queen, in the deepest area within the palace.