Wat Phra Thaen Sila At

What people venerate is the Phra Thaen Sila At, a rectangular laterite slab about 8 ft wide, 10 ft long and 3 ft high on a lotus base, under a gilded Chiang Saen–Lanna style mondop inside the viharn; devotees later added a carved, gilded wooden seat over it. There is no large principal Buddha — the slab itself is the sacred object.

A legend from the Panca Buddha Byakarana tells that the five Buddhas of this aeon, as Bodhisattvas, practised perfections here and agreed that whoever attained enlightenment would come and make it known. When the present Buddha came with 500 arahants, he ate on the stone slab, Ananda hung the alms-bowl on a jujube tree, and the Buddha rinsed his mouth into a laterite spittoon; he then stood on the next peak leaving footprints (Wat Phra Yuen) and reclined on another hill (Wat Phra Non). "Thung Yang" is said to come from "yap yang", to pause, since the Buddha paused here.

Scholars note the legend resembles the Lanna "Buddha travels the world" tradition and was probably composed no earlier than the 17th–19th centuries; firm history begins in the Ayutthaya period. In 1740 King Borommakot came to worship with three days of celebration, between 1754 and 1758 Ok Phra Si Ratchachai rebuilt the decaying viharn, and in 1770 King Taksin also came to worship.

In Borommakot's reign the old carved doors of the Phra Phuttha Chinnarat viharn in Phitsanulok were brought here. Some travel sites say they survive, but Wikipedia, Siam Rath and Silpa Watthanatham agree they burned in 1908.

Late in Rama V's reign came several notable visitors: Prince Damrong on 10 November 1898, Prince Naris on 6 June 1901 and King Chulalongkorn himself on 24 October 1901; Crown Prince Vajiravudh came in 1905 and 1907 and wrote of it in Lilit Phayap and Thiao Mueang Phra Ruang.

On 25 March 1908 a forest fire burned the temple, sparing only the kuti of Luang Pho Thammachak. The governor of Uttaradit, Phraya Warodom Phakdi, led a public subscription to rebuild the viharn with a mondop over the slab, as announced in the Royal Gazette on 23 May 1909. The new viharn largely follows the old plan but lacks the north porch.

In 1935 it was registered as an ancient monument; in 1940 the mondop was chosen for Uttaradit's provincial seal; and on 19 September 2006 the temple became a third-class royal temple. In 2019 the viharn hosted the province's consecration of water for the coronation.

On the viharn's south side grows the jujube tree of the alms-bowl, about 10 m tall, its trunk emerging from the wall and said to be over 200 years old. On 6 June 1901 Prince Naris recorded a north porch holding a stone spittoon about a cubit wide — the Buddha's rinsing spot — but that porch was removed in the rebuild after the 1908 fire, so today's stucco spittoon is probably not original; Theerawat Saenkham suggests two laterite pieces by the museum gate may be the original. Viharn murals depict royal ceremonies and duties of the Chakri kings.

A two-storey Lanna-style wooden folk museum shows fishing gear and old boats below, and basketry, tools, Sangkhalok ware, Sukhothai- and Ayutthaya-period Buddha images and a late-Ayutthaya naga-stair pulpit above. The claim that Phraya Phichai's real broken sword is kept here has not been confirmed by any source.

The Phra Thaen Sila At festival runs from the 8th to the 15th waxing day of the third month, around Makha Bucha, now over 12 days and nights. In 2026 it ran from 22 January to 2 February with nine processions, a dance by over 300 villagers, the jujube-stirring rite, alms for a hundred monks and more than 2,000 stalls. Devotees believe worshipping here three times in a lifetime leads to heaven.

The temple opens daily 08:00–17:00 and is free, museum included. There is parking, but the approach road is narrow and festival traffic heavy. Combine it with Wat Phra Yuen Phutthabat Yukhon, only about 300 m away, and Wat Phra Borommathat Thung Yang in one trip.