A commission I did for CBS Interactive a couple of years ago. The brief was to produce an image suitable to be reproduced on the wall of the lounge area in their San Francisco offices, incorporating a number of representative sites from the city. The wall was about 62' (18.9 metres) in length, so the original drawing is 4' long and had to be sufficiently detailed to be enlarged x18. A photo collage of streets was provided by staff in-house and I produced a final drawing from their rough, using my own photos and Google street view for details. It is to date the largest drawing I have completed.
I'd be very interested to hear if anyone has seen the image in situ (or has images); I have only seen a couple of photos of the lounge space taken for other purposes. I hope if I get back to SF sometime in the future I'll be let in to see it!