Kampaengkaew or the chapel boundary wall refers to the marble wall surrounding the main chapel. There are 8 sheltered gates and 8 sculpted boundary stones (or Bai Sema). The outer side of this boundary wall is engraved the images of mountains, trees and animals.
The outer side of Kampaengkaew around the main chapel is decorated with a series of 152 bas-reliefs depicting scenes from the Ramayana and described by Thai verses. These bas-reliefs were the wish of King Rama III to preserve the art of the grand shadow play, or Nang Yai, which was a famous Thai performance in the early Ayudhya period.
The art was less popular during Rattanakosin time because there were various types of entertainment such as Khone, or Thai classical dance drama, and drama, and with the reason that only skillful players can make a good performance. By duplicating the grand shadow show patterns as bas-reliefs, the art shall survive for generations and also reveal the finest craftsmanship to the world.
Many people were interested in this bas-relief decoration and tried to duplicate by rubbing chalk on pieces of transparent papers but the process over years deterioated the bas-reliefs, and it is now prohibited.