I think you could do awesome attic windows with your photos!! You could add sashing to each one to make them all the same size, using colors that blend best with each block, then do the attic window around them once they are all the same size.
After that, you can add borders in "roadway" or whatever you like to the size you want. Roadway= cut 3, 1" strips of slate gray and 3, 1" strip of white. Sew 1 strip set grey white grey and 1 set white grey white. Sew these together. You want to end up with a 1" strip of gray white gray white... as long as you need for each border strip. Cut 2, 3"-5" strips [as you desire] of the gray as long as you need for each border. Sew the 3" strips to each side of the gray and white strip which will be the dotted white line down the middle of the road.