This section of the wall made of bricks, because in this local and are inexpensive. The rest is to place small pockets cause connection of space and makes the building look solid, not tons.
The wall is made of brick, due to easily find local and affordable. This puts to rest a little space, causing coalescence of the area. And the building does not look solid.
This part made of brick wall due to easy and inexpensive, the local This is a place to rest a little space, make the connection of the area, and make the building look not dense.