It was a convention of Moorish design to decorate the heck out of walls, with maybe 5-6' of colorful geometric ceramic tiles from the floor, then rising to the ceiling with intricate carved-looking walls which often have some Koranic verses in them.
This from the Alcazar in Seville:
I learned three things about Moorish upper-wall treatment:
- This is not stone. It is marble plaster.
- This is not carved. It is made with molds while the plaster was soft.
- These walls, now white, were generally painted originally so it must have been jewel-like. It reminds me that Greek statues and columns, and even the statues of saints etc. on the outside of Gothic cathedrals, were also painted.
This is my pic of a plaster wall in the palace in the Alhambra.