Andromeda Harbor pictures - / this look unrealistic for me, maybe areal night scene with the black/grey sky would make look those space ships more real and blend with the scene background. Overall idea is great, so u are in the right way; just turn sky in black and merge it with your stared sky and let out the un-real colors. Then you would see the difrence, sure a photo taken by NASA ahhh i forgot add some fire behind the space ships / Your blue galaxy showing through the fog is a good effect, try maybe showing a tiny bit through all the fog to make it seem see through rather than a olid white fog... using a layer mask and the Dodge tool will let you show just tiny bits through as well as give it a uneven appeal.
Like in old Rome pictures - Found during recent escavations in Rome near "Colosseo" / I don't get it. Aside from that, making the images inside the whatever-it-is more stone-like would really help this chop.