The human eyeball is an incredible feat of evolution which is why some Creationists like to give God credit for it. Of course, if God did create it, she's clearly an imperfect God as evidenced by the fact that the image that the eyeball creates is upside down and flipped. Our brains correct the errors.
While we can see many of the external components of the eye, it's interesting to take a peek at what lies inside the eyeball. The Institute of Human Anatomy kindly sliced one open.