Phra That Phu Phek 

Phra That Phu Phek is on a mountain in Tambon Na Hua Bo. To get there, take the Sakon Nakhon-Udon Thani road for 22 kilometres and take a road on the left for 14 kilometres, then ascend 491 steps. The laterite pagoda is on a square base. Seemingly unfinished because it has no roof or pagoda top, it was built in the 16th-17th Buddhist century.

Moreover, this Khmer Ruins is special as it houses solar calendar, cube-shape rock, in its stupa. The ancient people used it for indicating position of the sun to indicate date for religious rites and agricultural seasons.