Preah Khan: Naga bridge over the moat.
Naga is a multi-headed serpent, which in this case has it's body supported by rosw of gods on the left side and asuras on the right side. This particular location is rather isolated so looters have made off with the giant figures' heads. This particular Naga/Gods/Asuras configuration depicts a scene of the "Churning of the Sea of Milk"; in addition the configuration sets up your journey from the world of 'men' to the realm of the gods.