Under the reign of the kings Jayavarman IV and Harshavarman II Koh Ker was briefly the capital of the whole empire (928–944 AD). Jayavarman IV enforced an ambitious building program. An enormous water-tank and about forty temples were constructed under his rule. The most significant templecomplex, a double sanctuary (Prasat Thom/Prang), follows a linear plan and not a concentric one like most of the temples of the Khmer kings. Unparalleled is the -high seventiered pyramid, which most probably served as state temple of Jayavarman IV. Really impressive too are the shrines with the twometer high lingas.