Ku Noi (small tower) at Ban Yang Ku was constructed in the 10th/11th centuries and located 300 metres to the west of Prang Ku that was constructed a couple of centuries later. Ku Noi has a unique architectural style, a complex of three towers on the same base, 1.5 metres high facing east. There are balconies on the east and west sides of the structure with a staircase on both sides. It is believed that the towers were made of wood since there are four post holes at all four corners of the base. The type of construction with three towers on the same base is similar to a more complete tower structure called Ku Ka Sing. The outstanding feature of Ku Noi is its contrasting style compared with Prang Ku nearby which has just the single tower on its base. Ku Noi was officially registered as a national ancient monument in November 1982.