In the hoard of the Dragon Queen module, there is a map of Greenest. None of the areas are labeled, but two of the sections tell me that 1 is the Keep, and 2 is the location of the old tunnel. However, in the section for the Mill and the Temple of Chauntea no area is mentioned, where on the map are they?
Based on the descriptions of the temple and the mill, and the fact that the areas marked 3 and 4 are not mentioned anywhere else, it seems clear to me that Area 3 is the Temple of Chauntea and Area 4 is the Mill.
Two reasons for this, one, there are only two walled sections on the map for the temple. One is marked 3 and the other is not marked at all. It's stated that the temple is the largest building, and looking carefully I see that the area marked 3 is even larger than the keep.
If you look closely at the building near area 4, you can see the extended office on the north side of the south side of the building, and being that its a normal mill, it has to be touching the river.
I've been reading Hoard of the Dragon Queen to run my own game and it appears that areas 1 - 4 correspond to the first 4 episodes in the campaign. Area 1 is the Keep on the map because all the missions within episode 1 start from the Keep. While it could be inferred that 2 - 4 relate to missions within episode 1, they also relate to general area each of those 4 episodes take place.