According to the information in its visitor centre, this temple was started by Khmer King Jayaviravarman (r AD 1002–06), although other records have it dated to as late as the 12th century. Regardless, Phimai is one of the most impressive Khmer ruins in Thailand. Though built as a Mahayana Buddhist temple, the carvings also feature many Hindu deities, and design elements at Prasat Phimai influenced Angkor Wat.
You enter over a cruciform naga bridge, which symbolically represents the passage from earth to heaven, and then through the southern gate (which is unusual since most Khmer temples face east) of the outer wall, which stretches 565m by 1030m. A raised passageway, formerly covered by a tiled roof, leads to the inner sanctum and the 28m-tall main shrine built of white sandstone and covered in superb carvings. At the centre of the Prang Brahmathat, in front of the main shrine, is a replica stone sculpture of Angkor King Jayavarman VII sitting cross-legged and looking very much like a sitting Buddha. The original is in the Phimai National Museum.
Knowledgeable local students sometimes act as guides, but few speak English. Luckily, a free brochure provides a good overview of the complex.