The shape of the Pentagon is an artifact of the shape of the property where it was originally going to be built. The location changed mid design but in the inte

The shape of the Pentagon is an artifact of the shape of the property where it was originally going to be built. The location changed mid design but in the interest of speed of design and construction they kept the original shape. Nothing more symbolic to it than that (this is why it's such an irregular pentagon, the shape was whatever the perimeter of the original space looked like).