As a boundry and expression and because the marques loved animals!
A prison wall, which is designed to keep people in.
An animal cell does not have a cell wall.
There is no cell wall in a animal cell but there is a cell wall in the plant cell.
Qin-Shi_Huang Built the Great Wall!
The animal does not have a cell wall, only a plant cell has one.
An animal cell has a cell membrane, not a cell wall.
Berlin Wall
because it was used to scare people who were trying to attack in the early 11th century.
Maya Lin
The animal cell doesn't have a cell wall, while the plant cell does.
I think that they were designed so that if the first wall fell to an attacking army they could retreat and make another stand on the second wall