The center of the Universe

Has anyone seen the center of the Universe? I have seen images of galaxies and I have seen attempts to see the center of our own galaxy but I have never seen an image of the center of the Universe. Of course some people say that there is no such thing as the center of the Universe but I often hear things such as the Universe is expanding. If it is expanding then there must be a center for it to be expanding from. So is it possible to determine where the center is? Assuming it is possible, then have astronomers taken a picture of there?