A group of tall White Towers that stood on - and gave their name to - the Tower Hills or Emyn Beraid that lay westward of the Shire. There were three Elf-towers on the Hills, of which one, known as Elostirion, was built taller than the others and stood out west of them on a mound of its own. According to legend it was possible to glimpse the Sea from that tower's top.²

The Towers were built by Gil-galad and the Elves of Lindon for Elendil, High King of the Dúnedain, in the last years of the Second Age. In Elostirion was placed the Elendil Stone, a palantír with the power to look out across the western seas and glimpse the Blessed Realm beyond. That Stone remained in its tower through the long centuries of the Third Age - more than three thousand years - until it was returned into the West by Gandalf aboard the White Ship.

In the Fourth Age King Elessar extended the borders of the Shire so that its western edge reached to the Tower Hills. In that new part of their land, known as the Westmarch, the Hobbits built a new settlement for its Wardens that they named Undertowers for the three Elf-towers that rose above it on their Hills.