This is the Lobby from the 5th St. Entrance at the EMP. I had the same problem as Steve...although they didn't tell me to move until after I had finished drawing the sketch. I wasn't to block the ticket sales. Of course I wasn't even close to it and there was no one in the sales' line.
To finish the watercolor portion. I would move back and forth between the cafe (where my paints were) to the spot I where I was originally standing. I needed to be able to see the reflections and shadows.