The Vihara of Wat Lai, commonly known as "The Nine-Bay Vihara," is a large rectangular building reflecting early Ayutthaya artistic styles. The structure features unique vertical slit windows, which are a characteristic architectural element of that period. A must-see highlight is the Stucco Reliefs decorating the exterior walls at both the front and back of the hall. These carvings depict the Ten Great Incarnations and the Life of Buddha with supreme delicacy and are considered among the most beautiful and well-preserved stucco works in Thailand. Inside the Vihara, prominent Buddha images are enshrined, and the hall serves as a gateway to the ancient archaeological sites located at the rear of the temple.