The White Towers were built on the Emyn Beraid by Gil-galad as a gift to Elendil, perhaps after the founding of Arnor (S.A. 3320).
The tallest of the three was called Elostirion and a palantír was kept there.
They were sometimes the destination of pilgrimage by Wandering Companies of Elves who would gaze to Valinor through the palantír. Such a band was led by Gildor Inglorion.
Portrayal in Adaptations
1988: J.R.R. Tolkien's War in Middle Earth
The White Towers can be seen at the background of the Towers Hills map.