Phnom Bok (Khmer: ភ្នំបូក) is a hill in the northeast of Eastern Baray in Cambodia, with a prasat (temple) (Khmer: ប្រាសាទភ្នំបូក) of the same name built on it. It is one of the "trilogies of mountains", each of which has a temple with similar layout. The creation of the temple is credited to the reign of Yasovarman I (889–910) between 9th and 10th centuries; established after he moved his capital to Angkor and named it Yasodharapura. The two other sister temples, named after the contiguous hills, are the Phnom Bakheng and Phnom Krom.The site of the three hills was chosen by Yashovarman I along with the Eastern Baray (where only the base of the central shrine is surviving). In the 10th century, these shrines had high religious value during the Angkorian rule. The temples called as part of an "architectural triad" brought about an element of experimentation in architectural style in the Angkorian period. From the astronomical references planned for three temples, out of the four noted alignments three, namely, equinox and winter and Solar Solstices could be observed from inside the western entrance of Phnom Bok hill temple, which is also known for the triple sanctuary dedicated to the Trimurti.