Preah Ko is among the earliest temples constructed in the Khmer capital of Hariharalaya, predating Angkor Wat by several centuries. Built around 879 AD under King Indravarman I, the temple marked an important transition to using sandstone instead of brick and laterite. Its three towered sanctuaries symbolized Shiva's sacred mount, the bull Nandi, giving Preah Ko its name meaning "Sacred Bull." According to historical inscriptions, King Indravarman I oversaw the construction of  Preah Ko as the state temple of the Khmer capital, dedicating its three central towers to their gods. Six smaller towers honored Indravarman's ancestors, including his parents, grandparents, and spiritual guru, a common theme in Khmer architecture and religious practice.

Today, much of Preah Ko's enclosures and buildings have deteriorated over the centuries. But the iconic sandstone towers remain,  heir intricate carvings and bas-reliefs depicting epic Hindu tales a testament to the advanced artistry of the ancient Khmers. As one of the earliest major sites at Angkor, those wandering the remains can glimpse the seeds of the region's grandest architectural achievements yet to come at Preah Ko. Its presence marked the first flowering of the Khmer empire's power and devotion.