Thom Temple (or Prasat Thom, Khmer: ប្រាសាទ កោះកេរ) is the main temple at the Koh Ker site, and was the state temple of Jayavarman IV when he moved the Khmer capital to Koh Ker in 921 or 928 CE – he may have had to wait for the death of Ishanavarman II to claim full sovereignty over the Khmer kingdom.
Thom Temple is a large temple, surrounded by moats crossed by two naga-lined causeways. It is part of an impressive architectural legacy left by Jayavarman IV at Koh Ker, and although largely in ruins the site offers some fascinating details if you have the time to take a day-trip from Siem Reap.
The pyramid called 'Prang', to the west of Thom Temple, at 36 m (120') high, is the largest ever built by the kings of Angkor. The linga that once stood at the top of Prang was about 4.5 metres (15') high.