In the northern parts of Ithilien, a stream ran out of Ephel Dúath and down towards Anduin. On its upper reaches, the stream ran over a lip of rock and formed a fine waterfall running down into a pool. Behind the waterfall was a recess in the rock, and from there as the Sun set a viewer looking out westward from behind the fall would see a spectacular show of colour and light as the ebbing sunlight filtered through the curtain of spray. This was Henneth Annûn, the Window on the West, or the Window of the Sunset (Elvish annûn could be translated as either 'west' or 'sunset').

In later times North Ithilien fell under the power of Mordor, and the Gondorians secretly hollowed out the recess behind the fall and expanded it to create a hidden refuge. From here, the Rangers of Ithilien set out on raids against the soldiers of the Enemy who passed through the land. It was here that Faramir brought Frodo and Samwise during their journey through Ithilien, and learning of the Ring he selflessly chose to release them, along with their guide Sméagol.