Built uniquely on a big slab of solid rock, Phra That Pha Ngao is a relatively small bell-shaped pagoda.  Another slab of rock stands in front of the pagoda as though it were the shadow.  Thus derived the name "pha-ngao", meaning the rock shadow.

Initially, this temple was called Wat Sop Kham.  Its former location was by Mekong River, and the temple was annually eroded by the tides.  Townspeople thus agreed to rebuild the temple further inland by a deserted temple at the foot of Doi Kham.  During the construction, they found under the base of the old Buddha image a magnificent Chiang Saen style statuette in subduing mara posture.  After half of the Buddha image was revealed, the excavation was stopped and a prayer has was built to cover it.  The image was called "Luang Pho Pha Ngao".