Lots of arches mean lots of paint. Since these are grey bricks, I'm starting with a spray of Humbrol 27 Sea Grey. Too much of that looks a bit monotonous so all the brick surfaces are dabbed with 67 Tank Grey using a sponge.
Normally I'd dry-brush bricks if painting, but there's so large an area to paint here that I need something quick and capable of a 90% job - and high-density sponge will do the job.
Sponges are underrated tools. One day, I'm sure a proper modeller will write them up in a proper finescale magazine and suddenly, the rest of the world will discover them. In the meantime, I'll keep dabbing on.