The Silmarillion

Elendil was cast up by the waves in the land of Lindon, and he was befriended by Gil-galad. Thence he passed up the River Lhûn, and beyond Ered Luin he established his realm, and his people dwelt in many places in Eriador about the courses of the Lhûn and the Baranduin; but his chief city was at Annúminas beside the water of Lake Nenuial. At Fornost upon the North Downs also the Númenóreans dwelt, and in Cardolan, and in the hills of Rhudaur; and towers they raised upon Emyn Beraid and upon Amon Sûl; and there remain many barrows and ruined works in those places, but the towers of Emyn Beraid still look towards the sea.

Isildur and Anárion were borne away southwards, and at the last they brought their ships up the Great River Anduin, that flows out of Rhovanion into the western sea in the Bay of Belfalas; and they established a realm in those lands that were after called Gondor, whereas the Northern Kingdom was named Arnor. Long before in the days of their power the mariners of Númenor had established a haven and strong places about the mouths of Anduin, in despite of Sauron in the Black Land that lay nigh upon the east. In the later days to this haven came only the Faithful of Númenor, and many therefore of the folk of the coastlands in that region were in whole or in part akin to the Elf-friends and the people of Elendil, and they welcomed his sons. The chief city of this southern realm was Osgiliath, through the midst of which the Great River flowed; and the Númenóreans built there a great bridge, upon which there were towers and houses of stone wonderful to behold, and tall ships came up out of the sea to the quays of the city. Other strong places they built also upon either hand: Minas Ithil, the Tower of the Rising Moon, eastward upon a shoulder of the Mountains of Shadow as a threat to Mordor; and to the westward Minas Anor, the Tower of the Setting Sun, at the feet of Mount Mindolluin, as a shield against the wild men of the dales. In Minas Ithil was the house of Isildur, and in Minas Anor the house of Anárion, but they shared the realm between them and their thrones were set side by side in the Great Hall of Osgiliath. These were the chief dwellings of the Númenóreans in Gondor, but other works marvellous and strong they built in the land in the days of their power, at the Argonath, and at Aglarond, and at Erech; and in the circle of Angrenost, which Men called Isengard, they made the Pinnacle of Orthanc of unbreakable stone.

Many treasures and great heirlooms of virtue and wonder the Exiles had brought from Númenor; and of these the most renowned were the Seven Stones and the White Tree. The White Tree was grown from the fruit of Nimloth the Fair that stood in the courts of the Bang at Armenelos in Númenor, ere Sauron burned it; and Nimloth was in its turn descended from the Tree of Tirion, that was an image of the Eldest of Trees, White Telperion which Yavanna caused to grow in the land of the Valar. The Tree, memorial of the Eldar and of the light of Valinor, was planted in Minas Ithil before the house of Isildur, since he it was that had saved the fruit from destruction; but the Stones were divided.

Three Elendil took, and his sons each two. Those of Elendil were set in towers upon Emyn Beraid, and upon Amon Sûl, and in the city of Annúminas. But those of his sons were at Minas Ithil and Minas Anor, and at Orthanc and in Osgiliath. Now these Stones had this virtue that those who looked therein might perceive in them things far off, whether in place or in time. For the most part they revealed only things near to another kindred Stone, for the Stones each called to each; but those who possessed great strength of will and of mind might learn to direct their gaze whither they would. Thus the Númenóreans were aware of many things that their enemies wished to conceal, and little escaped their vigilance in the days of their might.

It is said that the towers of Emyn Beraid were not built indeed by the Exiles of Númenor, but were raised by Gil-galad for Elendil, his friend; and the Seeing Stone of Emyn Beraid was set in Elostirion, the tallest of the towers. Thither Elendil would repair, and thence he would gaze out over the sundering seas, when the yearning of exile was upon him; and it is believed that thus he would at whiles see far away even the Tower of Avallónë upon Eressëa, where the Masterstone abode, and yet abides. These stones were gifts of the Eldar to Amandil, father of Elendil, for the comfort of the Faithful of Númenor in their dark days, when the Elves might come no longer to that land under the shadow of Sauron. They were called the Palantíri, those that watch from afar; but all those that were brought to Middle-earth long ago were lost.