Where do you find Thor's amulet on time tangled island?

On Time Tangled Island, go to the Great Wall of China (6 o'clock, 1593 AD ). At the upper right, atop the scaffolds, you will play a memory game against the old man. When you win, you get Thor's hammer shaped amulet (for the Vikings at 2 o'clock, 831 AD).

(*you should also pick up the barrel of gunpowder at lower right)