This image of NGC 4921, a large but gas-anemic spiral galaxy in the Coma Cluster ~320 million light years distant, is a recently released composite from the Advanced Camera for Surveys (dead since 2007) on-board the Hubble Space Telescope. The detail within the galaxy is exquisite and the numbers of background galaxies through cosmic space and time is jaw dropping. Get the large image or use the zoom facility.
p.s. The Spiral galaxy in the lower left corner, labeled here as one "with a very bright nucleus" appears to me to belong to the family of galaxies that harbor actively-feeding supermassive black holes in their centers known as "AGN" (active galactic nuclei), although I don't have any confirmation of that. Do ngc 3314 or parejkoj or Stupendous Man know either way?