Inside the old ordination hall (Ubosot) of Wat Sala Daeng, the sacred Luang Pho Yai is enshrined, an Ayutthaya-style Buddha image in the subduing Mara posture, a spiritual anchor for Saraburi people for generations. Exquisite murals adorn the interior walls, depicting the Buddha's life and traditional Thai life through artistically valuable line work. The atmosphere is solemn and peaceful, with natural light filtering through the old wooden windows, perfectly highlighting the beauty of the Buddha image and intricate stucco patterns, offering a profound sense of serenity and blessing to all who come to pay their respects.