Here's the obligatory Celestial observatory module. It's done the same way as pretty much every other piece. I added some Wills granite sheets to make a sidewalk. I found a load of ladders in my FLGS's bits box, which I think came from GW Lord of the Rings stuff.
The doors and windows (and maybe the barrel) come from Antenociti's Workshop, which has a whole bunch of useful stuff for this sort of thing.
It looks like someone was caught sneaking about around the back of the guildhouse. The graffiti is supposed to read 'Wizerds go home' but it's barely legible.