Wat Nakhon Chum, also known locally as "Wat Yai," is an ancient temple located near the western town wall within the historic city of Phichit. It is believed to have been constructed during the late Sukhothai or early Ayutthaya periods (approx. 14th-16th century AD). A distinctive architectural feature of its ordination hall (Uposatha) is the use of ventilation holes in the side walls instead of windows, a characteristic of Thai architecture from that era. The temple is highly significant as the original home of Luang Phor Phet, Phichit’s revered Chiang Saen style Buddha image, before it was moved to Wat Tha Luang. Currently, the temple houses Luang Phor Phan, the principal Buddha image used in historical rituals like the "Oath of Allegiance" ceremony for the city of Phichit.