Barad Nimras was a tower on a headland westward of Eglarest, built by Finrod Felagund in F.A. 65.
Its purpose was to watch the western seas, and warn of any naval attack by Morgoth's forces. As Morgoth never mounted any attack from the ocean, the tower was never in fact needed.
However, in the year after the Nirnaeth Arnoediad, Morgoth did launch a land-based attack on Eglarest and Brithombar, and Barad Nimras was torn down at that time by the very foes it was meant to guard against.
