The Tower of Orthanc

Orthanc was the black, impenetrable tower of Isengard built by the Dúnedain. By the Great Years and the War of the Ring, it was controlled by the wizard Saruman the White. It stood in the center of the Ring of Isengard, a daunting defensive wall built by the early Men of Gondor.

"A great ring-wall of stone, like towering cliffs, stood out from the shelter of the mountain-side, from which it ran and then returned again... one who passed in and came at length out of the echoing tunnel, beheld a plain, a great circle, somewhat hollowed like a vast shallow bowl: a mile it measured from rim to rim. Once it had been green and filled with avenues, and groves of fruitful trees, watered by streams that flowed from the mountains to a lake. But no green thing grew there in the latter days of Saruman. The roads were paved with stone-flags dark and hard; and beside their borders instead of trees there marched long lines of pillars, some of marble, some of copper and of iron, joined by heavy chains, to the centre all the roads ran between their chains. There stood a tower of marvelous shape. It was fashioned by the builders of old, who smoothed the Ring of Isengard, and yet it seemed a thing not made by the craft of Men, but riven from the bones of the earth in the ancient torment of the hills. A peak and isle of rock it was, black and gleaming hard: four mighty piers of many-sided stone were welded into one, but near the summit they opened into gaping horns, their pinnacles sharp as the points of spears, keen-edged as knives. Between them was a narrow space, and there upon a floor of polished stone, written with strange signs, a man might stand five hundred feet above the plain."

The tower was constructed out of four piers of stone and then hardened by an unknown process. No weaponry or magic that existed on Arda was known to be able to harm it. Until the Ents that besieged Isengard during the War of the Ring managed to inflict slight damage on the tower, but their efforts ultimately proved to be futile. When Gríma Wormtongue later threw the palantír of Orthanc from a high window, it fell on the stairs, causing the rail to snap and part of the staircase to break.

 
The only entrance to the tower was reached by a stair of twenty-seven steps, the door could only be opened with the Keys of Orthanc. Above the door there was a balcony, and many tall windows higher up.

 Isengard
The exact date of construction of Orthanc and establishment of Isengard is unknown; however it was likely built between SA 3320, the time of the establishment of Arnor and Gondor, and SA 3430, when the Last Alliance of Elves and Men was formed. Within the fortified walls of the tower was placed one of the palantíri, the Stone of Orthanc. Thus, Orthanc was now known as one of the seven towers of the Dúnedain, housing the seventh seeing stone brought back from Númenor by Elendil.

Third Age
Angrenost suffered greatly during the Great Plague of TA 1636, and the garrison steadily dwindled through the Age. Eventually the tower was closed and locked and its keys were taken to Minas Tirith to be kept by the Stewards of Gondor.

Eventually in TA 2710 the hereditary Captains of the fortress died out and Isengard came under the control of the Dunlendings. While they held the fortress, using it as a base for attacks on the Westfold, they could not gain access to the impenetrable tower. Following the Long Winter of TA 2758, the Dunlendings were besieged and starved into surrender by Fréaláf Hildeson. Then Saruman put in an offer for the control of Isengard and both King Fréaláf and Steward Beren embraced the proposition with open arms. Thus, the wizard was handed the keys to Orthanc as Warden of the tower.

 Saruman and the Stone of Orthanc
Later, Saruman's mind was corrupted and fell under the control of Sauron when he used the Stone of Orthanc for the first time. Desiring power for himself, he took Orthanc for his own in TA 2953.

 Gandalf's Rescuer
In TA 3018, Gandalf rode to Isengard to meet with Saruman. It was then that the wizard declared his true thoughts regarding his desire to be ruler of Men, to possess the Ring, and to join Sauron in his evil deeds. Gandalf refused Saruman's offer to join him and Sauron. Subsequently, the wizard held Gandalf captive on Orthanc's pinnacle until he submitted in telling the location of the One Ring. After many weeks of imprisonment, Gwaihir, the Lord of the Eagles, came and looked for Gandalf and bore him away.

 Battle of Isengard
Only months later, the Ents of Fangorn Forest launched their attack on Isengard. By the next day, only the tower of Orthanc remained, as it was hewn of one piece of impenetrable rock, and the plains below had been completely destroyed, leaving a desolate land of water and mud. Three days after the battle, Théoden, Éomer, Gandalf, Aragorn, Legolas, and Gimli approached Orthanc past a desolation of wreckage caused by the Ents including a huge blood-ridden white hand, and climbed its stair. They parleyed with Saruman, who remained inside the tower and spoke to them from a balcony above the door. After Saruman refused to cooperate and attempted to control the Rohirrim riding with them, Gandalf cast him from the Order of Wizards and the White Council, breaking Saruman's Staff. After the confrontation, Gríma Wormtongue—who was inside the tower at the time—threw the Stone of Orthanc at the party outside as a parting shot, missing both Gandalf and Saruman as he was unable to decide who he hated more.

Several months later Saruman was able to convince Treebeard to let him go, however Treebeard demanded and received the Keys of Orthanc from Saruman, handing them over to their rightful owner, King Elessar when he later visited.

Fourth Age
One of King Elessar's first tasks he had set was the restoration of Orthanc. He ordered that the palantír should be recovered and returned to the tower. Then Orthanc was searched and many secrets were revealed. It was clear that Saruman had been hoarding many ancient treasures and heirlooms during his time there. With the aid of Wormtongue, Saruman had acquired many jewels and heirlooms belonging to the House of Eorl. Soon a hidden door was found by Gimli and inside a casket they found two precious objects: one of which was a small gold case attached to a chain - this was used by Isildur to bear the One Ring; and second of which was the Elendilmir - the 'white star of Elvish crystal upon a fillet of mithril' that had been lost since Isildur's demise. Elessar received the Elendilmir with reverence and took it with him as he established his full kingship of Arnor. It was thus revealed that Saruman had found items worn by Isildur himself, and was speculated to have found and burned Isildur's bones as an insult.

Orthanc and the plains of Isengard around it remained part of the Reunited Kingdom. However, King Elessar granted the Ents complete self-governance of the area surrounding the tower. This new forest became known as the Treegarth of Orthanc.

Pinnacle of Orthanc
 Orthanc roof sign
The Pinnacle of Orthanc was the summit of Saruman's tower. Its corners were razor-edged points with room for at least two men to stand. It was accessed by a flight of thousands of stairs, which Saruman would use to reach the top and observe the stars.

It was here where Saruman imprisoned Gandalf at the start of the War of the Ring, which caused him to be delayed in meeting with Frodo. He was rescued by the Great Eagle Gwaihir, sent by Radagast the Brown.