Henneth Annûn was a hidden Gondorian outpost northeast of Cair Andros in North Ithilien. This secret dwelling consisted of a cave behind a west-facing waterfall, the Window-curtain, overlooking an oval pool. The cave had been excavated by the stream feeding the waterfall, which originally fell from the hole in the cliff constituting the window in the name, but that stream had since been diverted and the tunnel sealed, save for a concealed entrance.
This region borders Cair Andros and North Ithilien.