The Great Vihara was constructed or majorly renovated during the reign of King Narai the Great for significant religious ceremonies. Its most striking feature is the “pointed-arch windows (Gothic style)”, reflecting architectural influences from the West. The building is grand and spacious, built with brick and stucco, featuring large entrance doors at the front and back aligned with the main prang. The thick walls were designed to support a wooden-framed tiled roof (now collapsed) and included light openings to brighten the interior. This architecture stands as a testament to an era when Siam prospered and extensively embraced international cultures.