On the Thonburi side of the Chao Phraya river and along Khlong Bangkok Noi and Khlong Bangkok Om Noi, several temples have beautiful, interesting and certainly pictoresque mural paintings.
These are not really accessible for the visiting tourist. They certainly do not feature on any guided tourist tour. The temples housing these painting are often in a state of disrepair, and locked to the general public. One has to be able to speak Thai language, be patient and assertive at the same time, to get these treasures unlocked.
Unfortunately, it can be expected that most of what you see here, will disappear in the real world in the next 50 years or so. The stucco murals really are suffering a lot, and not sufficient effort and money is being spent on preserving them.
Ancient places like Padmanabhapuram, Krishnapuram and Mattancherry are enriched with murals. Temples like Padmanabha Swami temple, Panayannarkavu, Pundareekapuram, Ettumanoor, Thruprayar, Kottakkal, Thotteekkalam and Lokanarkavu also have walls decorated with murals. The churches like Kottayam Cheriya Palli, Cheppad Church, Ankamalli Church, Kanjoor Church and Akkapparambu Church also have murals, to decorate their walls. All these are done in Kerala style.