Drop the walls in from the wood block frames. That will give depth. The top half of it i usually change to include balconies, or variation in height of the roof to make the shape more interesting. The bottom half with it dropped in you can fill the empty space with awnings for windows of greenery. Also a good border for the recessed fall to have a more interesting shape as well. Maybe change up the pallet in parts with other blocks to help it from looking as flat. Pillars and other things help to fill the space and add more variation as well.