my vote for most interesting part of the human skeleton.
Through that hole is where the spinal cord and the brain connect. It is the gateway of the central nervous system housing the very place where 100 billion nerve cells and trillions of support cells meet with the body via the spinal cord. Essentially it is the tunnel through which all the information received by your body passes through to be integrated. Human experience, life, it all passes through that hole like a current of electricity through a wire, or a light beam through mist. A miracle so quiet it could escape the sound of fingernails growing in the night.