The building and general scene looks great! The moss and/or ivy on the buildings is a little weak, though. Maybe try looking at some of the model train terrain products like those made by Woodlands Scenics? I've looked at the other pictures too, this is a great scene, must be neat to play in!
Is that the ancient McDonald's sign I see behind the tree? (to the left of the stairs). Geez, Mickey D's really is everywhere! (the terrain looks good too! ;) )