Holy crap, this is an amazing photo! Photographer Chris Kotsiopoulos writes:
After wondering for some time whether it was possible to image the sky from one morning to the next where I live in Athens Greece, I decided to give it a try. After hours of planning and preparation, and a full day of shooting, the image above is the result of this labor of love. It took me about 12 hours to pull together and process a single image that included over 500 star trails, 35 shots of the Sun and 25 landscape pictures.
He offers more details on how he accomplished this amazing photo in this Greek Sky Forum post.