Kampaengkaew or the chapel boundary wall refers to the double marble walls around the main chapel. There are 8 sheltered gates and 8 sculpted boundary stones (or BaiSema). The Outer side of this boundary wall is mountains, trees and animals.

     The Outer side of balustrades around the main chapel is decorated with a series of 152 selected bas-reliefs depicting scenes from the Ramayana as described by Thai verses. These bus-reliefs were the wish of King Rama III to maintain the art

of the shadow show, which was a famous Thai style entertainment since the beginning of Ayudhya period. The art was less popular during Rattanakosin period because there were other kinds of entertainment such as khon (Thai classical dance drama) and drama, and with the reason that only skillful players can make a good performance. By duplicating the shadow show as bas-reliefs the art will 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. Souvenirs from this duplication was once very popular as a Wat Pho symbol, but the process over many years damaged the bus-reliefs, and it is now prohibited.

      Phra Maha Stupa or Phra Prang , there are 4 pagodas at the corners of outer-side of the chapel yard. This kind of pagoda is specially termed “Phra Agghiya chedi”.

      Each is tiled with marble, with 4 Khmer-style statues, tin gilded with gold leaves and decorated with glass inlay, of the so-called “Catulokapala” – the Guardian Divinities of the Four Cardinal Points- on its 4 corners.

      The stupa on the northeastern corner is called “Phra Buddha Manggala Kayabandhana Mahastupa”, the southeastern “Phra Buddha Dhammacak Pavattanapaduka Maha Stupa”, the southwestern “Phra Buddha Vinaiyapitaka Sucigkara Maha Stupa”, the north-western one “ Phra Buddha Abhidhamma Dharavasi Parikkhara Maha Stupa”.