First, get a device that beeps when you are near a crystal. To do this, go to the picture of Nathaniel Payne and place the two pots you found in the basement there. The picture will open and you will get it. The first crystal is in the small Civil War section near the guard. Blow open one of the houses. The second crystal is under one of the ice age animals. It is the one up in a cave. The third crystal is in the center of the sun diagram. The final crystal is in the corner of the Egyptian section. This last crystal has a map behind it with a symbol by each section. Remember the symbols because they represent the order that the crystals go into the wall.