Prasat O Ka-aek
Be aware, there may be two different temples in the west of Roluos which are called Prasat O Ka-aek or Au Ka-aek. The other one is a more hidden ruin and lies just west of the Preah Ko compound.
The pictures on this webpage are from another temple at the road leaving from Bakong into western direction. You will see it after approximately two kilometres on the right-hand side. It is also called Trapeang Ka-aek or Spean Ka-aek, though "trapeang" means "pond" and "spean" means "bridge" and there’s neither a pond nor a bridge close to it.
The single Prasat is without roof and the walls are partly broken. But the false doors are decorated with some fine carvings, tendril ornaments and figures on Kala masks. Some decorated slabs and colonettes lie scattered on the ground in front of the temple.
Morning hours are more recommendable than the afternoon for taking pictures. A ticket is not required.