Aldburg (O.E. 'old fortress') is a hill fort and settlement in Rohan, in the region known as the Folde, some miles to the southeast of Edoras. Aldburg was initially the capital of the realm, where Eorl the Young, the first King of Rohan, founded his hall in T.A. 2510. Though his son, King Brego, moved to Edoras early in Rohan's history (T.A. 2569), Aldburg remained the residence of the descendants of Éofor, Brego's third son. One of these descendants was Éomer, who was also a nephew of King Théoden. At the time of the War of the Ring, Éomer was the Third Marshal of the Mark and became heir to the king.
Amon Hen is a hill located on the western bank of the river Anduin, at the southern end of Nen Hithoel, the lake above the Falls of Rauros. It was one of the three peaks at the Falls of Rauros at the southern end of the Emyn Muil, the others being Amon Lhaw, the Hill of the Ear, and Tol Brandir, an island located between the two hills. The Seat of Seeing was built at the summit of Amon Hen, serving as a watchtower for the northern borders of Gondor. It was constructed in the early days of Gondor.
In The Fellowship of the Ring, the Fellowship travelled down the Anduin from Lothlórien to Parth Galen, the lake-side lawn at the feet of Amon Hen. But here the Fellowship was broken: Boromir attempted to take the One Ring by force from Frodo Baggins, who fled; Boromir was shortly afterward killed defending Meriadoc Brandybuck (Merry) and Peregrin Took (Pippin) from Orcs, who had been sent by Saruman to capture the Ring; and the Orcs absconded with Merry and Pippin. After Frodo escaped from Boromir, he sat upon the Seat of Seeing while still wearing the Ring, and was able to see events hundreds of miles distant. From Amon Hen, Frodo and Samwise Gamgee crossed the Anduin on their way east to Mordor, while Merry and Pippin were carried by Saruman's Orcs in the direction of his hold at Isengard, and the rest of the Fellowship set out in pursuit of the Orcs.
Tolkien's aerial view of the Emyn Muil shows Tol Brandir to be much taller than Amon Hen and Amon Lhaw. The sketch is published in J. R. R. Tolkien: Artist and Illustrator.
Amon Lhaw (S. 'Hill of the Ear') is one of the three peaks above the Falls of Rauros which drained the lake known as Nen Hithoel, it towered amongst the Emyn Muil on the eastern banks of the Anduin. Its twin, Amon Hen (The Hill of Sight), lay upon the western bank. Between them, at the centre of the stream above Rauros, was the island peak Tol Brandir upon which none had ever set foot.
Although at one time Amon Lhaw had been on the northern boundary of Gondor and a high seat was built there (probably called The Seat of Hearing), this was no longer the case at the time of the War of the Ring; by then, it had long since fallen under the influence of Mordor. Also called the Hill of Hearing and perhaps Hill of the Ear in Westron.