The Astronomy Picture of the Day site is one I often look at. Here are two recent and two older images that I particularly recall.
Melk Abbey manuscript c.1490 showing the Ptolemaic view of the universe, pre-Copernicus.
M101 pinwheel galaxy everyone's idea of a galaxy.
In the Shadow of Saturn a view of Saturn's rings, looking back towards Earth, which is just a tiny dot.
Cat's eye Nebula like a flower in the sky.